Abstract:
Apparatus for measuring airflow at heating, ventilation, air conditioning, and refrigeration (HVAC) diffusers is described. The apparatus comprises a capture hood comprising a lightweight carbon fiber frame, a fabric skirt portion supported by said frame, and a base. A grid-type probe is disposed within the capture hood. An airflow sensor module is carried by the capture hood and arranged to sense airflow data. The airflow sensor module comprises a transmitter to wirelessly transmit airflow data to a control module. The apparatus further comprises retainer apparatus to retain the capture hood in flow communication with a diffuser.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/136,814 filed Aug. 11, 2011 titled Wireless Sensors System and Method of Using Same. 
         [0002]    This application and application Ser. No. 13/136,814 claim the benefit of Provisional Patent Application No. 61/401,336, filed Aug. 11, 2010, entitled Wearable Wireless Instrument System; and this application claims the benefit of Provisional Patent Application No. 61/463,549, filed Feb. 19, 2011, entitled System of Wireless Sensors with Wearable Controller. 
     
    
     FIELD OF THE INVENTION 
       [0003]    The present disclosure generally relates to measuring environmental parameters such as temperature, humidity, and pressure. More particularly, the disclosure relates to system and method for measuring environmental parameters and wirelessly transmitting information to a display device. 
       BACKGROUND OF THE INVENTION 
     1. Problems 
       [0004]    Instruments are often used to measure air and water parameters such as temperature, humidity, pressure, air velocity, airflow, and many other environmental parameters. These measurements take place in buildings, factories, outdoor weather stations, and other locations. Instruments may be rack-mount, desk mount, mobile/handheld, or other. 
         [0005]    A typical instrument consists of a plastic case enclosing a printed circuit board with microprocessor-controlled electronics, memory, one or more sensors, and a display. The sensors are often in a wand-shaped probe. Various probes, large and small, are designed to collect environmental samples for sensing, measurement, display, and storage. When using this type of instrument, a user has both of his hands occupied, one to hold the meter, and one to hold the probe and extend it to the location of interest, such that a user&#39;s hands are not available for other tasks. Cables, wires, and/or tubes typically dangle between the probe and the meter. 
         [0006]    For Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC) applications, engineers and technicians who work in buildings deal with many different types of instruments. There are building automation systems (BAS), fire safety systems, occupancy detection and security, permanently installed instruments such as pressure, temperature, humidity, and airflow, with some nearby and some remote sensors, and portable instruments for such parameters as temperature, pressure, humidity, sound/noise, light intensity, carbon dioxide, velocity, flow, and others. As engineers and technicians move throughout the structure to solve problems, they often lack access to required information, and must either move to a central location for access to data, or must carry a variety of instruments with them. Lacking is an overall system for quick access to desired information. 
         [0007]    Engineers and technicians commonly require two types of measurements. One is immediate feedback when finding and/or solving a problem, as when measuring the temperature of air being supplied at a diffuser. The second is a series of measurements at regular intervals from one or many locations, for comparison and contrast of parameters that may indicate problems that occur over time. 
         [0008]    Measurement problems are important to the HVAC industry. Measurement disputes are often at the heart of conflicts over HVAC performance issues such as uncomfortable buildings, inefficient energy performance, and inability to maintain specified parameters such as adequate positive pressure in hospital operating rooms. These conflicts frequently result in anger, confusion, disputes, cancelled contracts, lawsuits, mediation, and unhappy building owners, tenants, and workers. Contributing to these conflicts is that measurements of HVAC-related building parameters such as air and water temperature, humidity, pressure, velocity, and flow are perceived to be inaccurate and unreliable, so dissatisfied parties often challenge their validity. Accordingly, an improved system and method that improves the accuracy and speed of measuring building parameters and the safety with which they are measured by technicians are desired. 
         [0009]    Flow, airflow, and water flow are industry terms that relate to the volumetric rate of fluid flow expressed in units such as cubic feet per minute (CFM) or gallons per minute. Airflow is usually not measured directly. It is usually calculated by measuring the velocity of air at multiple points in a cross-sectional plane, calculating an average velocity at the plane, and then multiplying by the known area of the cross-section. The plane where measurement takes place might be across an air duct, in a duct-shaped probe like a capture hood, or at the opening of a fume hood, door, or window. 
         [0010]    These are long standing problems in several different measurement applications related to HVAC. 
       Exemplary Problem 1 
     Wasteful Back and Forth Travel 
       [0011]    Technicians are concerned with the occupied spaces and the system controls that are spread all over the building, from the facilities space with the fan, coils, pumps, pipe, compressor, and/or evaporation tower, through the duct system to the occupied spaces. In many cases the point of interest to an operator or technician is some distance removed from the forces or controls that cause the conditions at the point of interest. To adjust the controls for improved operation requires a lot of back and forth movement during a repetitious cycle of measurements and adjustments. They must measure at one location, then move to another location to effect a repair or adjustment. Then they must return to the original location to measure the impact of the change. This wastes time and leads to approximations. What is needed is real-time data at the point of control, so changes can be readily evaluated and adjustments made precisely as specified. 
       Exemplary Problem 2 
     Poor Communication within Teams 
       [0012]    A second problem of conventional practice in HVAC measurements relates to technicians who work in teams of two or more. Measurements are usually taken by one person. Team members who need the information must receive it from the one who took the reading, usually by speaking, shouting, or walking to a conference, or sometimes via walkie-talkie or cell phone. 
       Exemplary Problem 3 
     Instrument Limitations 
       [0013]    A third problem with existing instruments is that they provide limited information with each measurement. For instance, during a velocity traverse of an HVAC duct, the technician may need to record a series of air velocity measurements, plus the air temperature, air humidity, barometric pressure, and the duct static pressure. The meter he uses may display only one of these parameters at a time. Further, he may have to change the setup of the meter between measurements to acquire all of the necessary information. Accordingly, an improved system and method to provide technicians with more of the information relating to a particular application are desirable. 
         [0014]    One reason for this problem is that general-purpose instruments are being used for applications that are specific to operations such as air balancing. For instance, a differential pressure meter is attached via rubber tubes to a Pitot tube, and the combination used to determine the air velocity in the duct. It is desirable to have a tool designed specifically for HVAC applications such as duct velocity traverse. 
         [0015]    Engineers and technicians do not have one system of convenient access to required information. Instead, they often use a wide variety of instruments, including BAS, temperature meters, humidity meters, air pressure meters, water pressure meters, air flow meters, water flow meters, etc. It is desirable to have the capability to quickly access any required measurement as they move throughout a building to find and fix problems. It is desirable to have a system and method that allow engineers and technicians to measure immediately and interactively, while also providing means to datalog the same measurement types at the same locations at regular intervals over a period of time. 
       Exemplary Problem 4 
     Instrument Style 
       [0016]    A fourth problem in conventional practice has to do with the size and shape of instruments and the intended method for taking measurements. Many instruments are designed in the form of a hand-held probe attached with a coiled cord to a handheld meter. Taking a measurement occupies a technician such that he cannot do anything else with his hands at the same time. In connection with the measurements taken, it is often necessary for a technician to use his hands to climb a ladder, drill holes, screw or unscrew, or move a lever. A technician may have to set down an instrument in order to effect a repair or make an adjustment, and in so doing will lose sight of the meter readings. The existing type of instrument is clearly cumbersome in this context. It is desirable to have instruments that are relatively small, relatively light in weight, and easy to manipulate in the environment of interest. I 
       Exemplary Problem 5 
     Instrument Size and Weight 
       [0017]    Airflow capture hoods are used to collect the air being supplied by diffusers. One popular capture hood weighs 10 pounds and must often be held tightly against a ceiling diffuser. If the ceiling is high, the technician must employ a ladder. This type of procedure is difficult for most people to perform properly hour after hour, day after day. Fatigue, strain, and injuries are common. It is therefore desirable to have instruments that are relatively small, relatively light in weight, and easy to manipulate in the environment of interest. 
       Exemplary Problem 6 
     Accuracy and Reliability 
       [0018]    As a result of Problems 1 through 5, measurements are often performed too quickly, improperly, inaccurately, or not at all, due to short cuts taken by technicians under stress. For instance, a technician who realizes that a measurement is likely because of circumstances to be inaccurate or unrepresentative is more likely to compromise, estimate, or skip the measurement. It is desirable to have instruments that are quick and easy to use and that can be trusted to achieve an accurate result. 
       Exemplary Problem 7 
     Manpower 
       [0019]    Current practice is to use two-man teams, for some of the reasons listed above: safety; heavy, cumbersome instruments; working above the ground on ladders or scaffold; needing to be in two places for measurements and control adjustments. Accordingly, systems and methods that require less manpower are desired. 
       INDUSTRY APPLICATIONS 
       [0020]    The following use cases are some industry procedures that illustrate the long standing problems mentioned above. 
       Set Point of Duct Static Pressure 
       [0021]    In HVAC duct systems it is important to maintain duct static pressure setpoints at various locations in a duct system in order to maintain airflow through the duct and diffusers. For instance, a building engineer might specify that the fan generate a duct pressure that is 3 inches of water column above the ambient pressure in the building (static pressure), that the secondary supply air ducts that feed each floor be maintained at 2.5 inches of water column, and that the system of valves and dampers be adjusted such that the most remote air diffuser will be supplied air at a pressure of at least 0.5 inches of water column. If pressure is too low, the diffusers will not distribute conditioned air as designed and building comfort will suffer. If pressure is too high, energy is wasted by running the fan too fast. The electric power used increases at the cube of the duct pressure increase. For instance, if the fan speed is increased to raise the remote duct pressure to 0.55 inches, only 10% higher than required, the fan will use 30% more electric power than required. (The calculation has the form of 1.1×1.1×1.1=1.3.) 
         [0022]    Current procedure requires a technician to measure the pressure, then move through the building to adjust the fan and the dampers. He then returns to measure pressure again. This cycle of measurement and adjustment will be repeated until the specified result is achieved. Sometimes the fan is a long distance from the point being measured, and on a different floor. This repetitive procedure requires a lot of time and effort, and leads to the technician settling for some safe guard-banded pressure instead of achieving the precise result desired. This is one of the main sources of wasted energy in buildings. It is desirable for applications like this to provide a technician with a an improved system and method for making measurements at the point of interest, and delivering results continuously to him where and when he is making the adjustment at the point of control. 
       Setting Outside Air Ventilation Controls 
       [0023]    One of the most important functions in HVAC is to provide adequate ventilation, which is done by bringing in fresh air to replace used air that is infused with odors, body moisture, carbon dioxide, and other products of the indoor environment. This is a health issue, not just a comfort issue, and is strictly regulated. The volume of outside air needed is calculated according to industry formulas. Then the outside air dampers and control fans are adjusted by a degree estimated to achieve the correct volume. 
         [0024]    This procedure often involves the measurement of several temperatures: outside air, indoor supply air, indoor return air, and the air inside the mixing chamber. The temperature in the mixing chamber is related to the temperature of return air and outside air, and the volumes of each. Adequate ventilation can be determined by measuring and comparing the different temperatures. Adjustments are made, and then the four temperatures are measured again. This is repeated until the mixed air temperature reaches a specific function of outside air and return air temperatures. Needed is a way to measure all four of these temperatures concurrently, and provide them in real time to the technician at the point of control, so he can quickly see the result of his adjustment. 
       Damper Setting and Proportional Balancing Method 
       [0025]    Two technicians generally work together to adjust dampers to set airflow through supply diffusers to match specifications. One tech lifts up and holds a capture hood airflow probe against the diffuser, which is usually on the ceiling. He reads a meter attached to the capture hood. He calls out the reading. The second technician climbs a ladder and locates the damper adjustment above the ceiling tiles. He adjusts the damper until the measurement called out meets the specification. Needed is a way for the person doing the adjusting to be able to see the results of the adjustment in real time. 
         [0026]    The meter must measure the temperature of the supply air in order to make an accurate reading. However, it takes a long time for temperature probes to properly register the actual temperature of air coming out of the duct, so technicians often ignore this requirement. Needed are means for quickly measuring the actual air temperature and using it to improve the accuracy of the measured airflow. 
         [0027]    Also needed is a way for one person instead of two to perform this task. A stand or jack can be employed to hold the capture hood against a ceiling diffuser. This helps prevent the heavy and bulky hood from losing a seal, and it prevents weariness and injury to the operator. However, it is still necessary for the adjustor to have the measurement shouted over to him, or, if working alone, for him to leave the damper, climb down from the damper, walk to the capture hood, see the result on the meter, and return to the damper to make another adjustment. 
         [0028]    A related industry method is the Proportional Balancing Method. Specifications often require that supply air diffusers be adjusted so that their airflows are all the same percentage of the specified airflow. For instance, if there are three diffusers, and the air available is 10% less than specified, then each air diffuser should be set to 90% of the specified flow. If the specified flows were 300, 200, and 100 cubic feet per minute (DFM), then the post-adjustment measurements should be 270, 180, and 90 CFM. However, duct systems with dampers and supply diffusers and return grills have paths to resistance of airflow that are interrelated. That is, if one path is made more resistant to airflow by adjustment of a damper, the air adjusts and goes somewhere else. This makes it difficult to set dampers the way they should be set. Usually the diffuser furthest from the fan is set by adjusting its damper. Then a second damper is adjusted. Then, the first diffuser must be measured again to determine if the second adjustment caused such a change in duct airflow distribution that the first diffuser airflow became out of range. The two dampers are adjusted again until they are both in spec. Then a third damper is adjusted. This continues until all diffusers on the same branch of the duct system are within the specified range. This takes a long time, with many repeated measurements. Each diffuser must be measured independently, one at a time, despite the fact that they are part of a connected and interdependent system. This method is repetitious and wastes time. It leads to compromise and non-ideal outcomes. What is needed is to see the effect of changes in real time. 
       Evaluation of Thermal Transfer Coil Efficiency 
       [0029]    It is often important to measure the moisture content of air in ducts. A critical HVAC function is thermal energy transfer via coils. For instance, energy is used to remove moisture and cool air from outside that enters hot and humid. HVAC technicians must measure the temperature and moisture content of air before and after it is exposed to the bank of coils in order to determine whether the system is performing properly. Then the system is exercised to vary the load on the coils while measurements are taken. Needed for this application are means of concurrently viewing the incoming air temperature and humidity as well as the outgoing air temperature and humidity. 
       Water-Side Balancing 
       [0030]    In HVAC machine rooms there are pipes running to and from the chillers, evaporators, pumps, and valves. It is necessary to measure water temperature and pressure in various places. These measurements are related to each other. At present is it time consuming to make iterative measurements between many adjustments to pump speeds and valve setting. Needed are means to see a variety of water pressures, temperatures, and water flows concurrently. 
       Velocity Traverse of Air Duct 
       [0031]    The volume of air moving through a system of ducts is a frequently required figure in HVAC. System designers specify the air characteristics at specific locations throughout the duct system: leaving the fan, passing through filters and coils, delivered to the main duct on each floor, branch ducts, and finally supply air diffusers. The same is true for the return path to the fan intake, which begins at return air grilles in the occupied spaces, then past return air fans and dampers, mixing chambers where outside air enters, and into the main air handler intake. At each of these key points in the system, air balancers measure airflow volume, temperature, humidity, and duct static pressure. 
         [0032]    Airflow volume is not measured directly in a duct. Instead, the average velocity of the air is determined and multiplied by the cross-sectional area of a plane across the duct. Since the velocity of air varies significantly over such a cross-sectional plane, an average velocity must be determined by measuring many different locations in the cross-sectional plane, and then averaging those values. The industry has derived standards for the locations to be measured, that are specified in terms of the distance from the duct walls. 
         [0033]    A technician first measures the length and width of a rectangular duct, or the diameter of a round duct, and calculates the cross-sectional area, adjusting for the thickness of the duct walls and any insulation or other internal obstructions. Then he consults a table provided by an engineering society such as ASHRAE for the locations of the points in a matrix on the duct cross-sectional plane. The technician drills holes in the duct to allow the Pitot tube to be positioned at the each point in the matrix. It is convenient to think about horizontal and vertical planes across the duct. The technician marks his probe with tape so he can see how far into the duct to insert it to reach each traverse point. Then he makes a velocity measurement at each traverse point, one after the other, recording or storing each reading as he goes. In most cases it is necessary to measure between 16 and 150 different traverse points. This is a laborious and error-prone operation. 
         [0034]    During a duct velocity traverse, a technician stands high on a ladder with his head in the dark space above the ceiling tiles. With traditional equipment, he holds a meter in one hand and a velocity probe such as a Pitot tube in the other hand. Between the meter and the Pitot tube are rubber hoses that dangle down and are prone to getting caught on projections. The hoses are also prone to swinging during measurement, which can affect the accuracy of the measurement. 
         [0035]    A proper velocity measurement also requires determining the air density. Density in turn requires barometric air pressure, temperature, and if possible, humidity. Barometric pressure is easily measured inside the meter and is not a problem. Temperature and humidity present another problem for a technician. Already burdened by meter, probe, and dangling tubes, he must manipulate a temperature probe from the meter into the duct and keep it lodged there while performing the 16 to 150 separate velocity measurements mentioned above. 
         [0036]    Once the velocity traverse has been completed and the Pitot tube withdrawn from the duct, a technician performs a separate setup to prepare to measure duct static pressure. A traditional meter must be removed from a Pitot velocity mode and placed into a differential pressure measurement mode. Then the user changes the hose connections between the Pitot tube and the meter. Finally, the user reinserts the Pitot tube into the duct and performs the static pressure measurement. 
         [0037]    In summary, the airflow, velocity, temperature, and pressure measurements required are difficult and time consuming to obtain using traditional instruments and methods. Such a measurement process may require three different duct insertions, three different measurement modes on the meter, and two different hose configurations. The bulky meter may weigh a few pounds, and the user may have difficulty manipulating it with one hand to press the control keys while manipulating the Pitot tube with the other hand and keeping the tubes and temperature probe from swinging and getting tangled. 
       DESCRIPTION OF RELATED ART 
     Existing Products and Technologies 
       [0038]    Recently some wireless meters have appeared (e.g., Testo) eliminating the conventional coiled cable between the probe and the main body of the meter. However, one hand is still necessary to hold the meter, and another is required to hold the sensing probe. The sensing probes are still as large and ungainly as conventional instruments. They can be placed and left on a desk or file cabinet or floor, but are difficult to place at the point of interest for HVAC technicians, such as slotted air diffusers or water pipes. 
         [0039]    Another type of wireless device has been used in HVAC applications. This is a wireless sensor network for datalogging, collecting environmental data at regular intervals. For example, at intervals of 10 seconds or one minute, a sensor makes a measurement and transmits it wirelessly to a stationary data collection and storage point. Once in a while the collected and stored data can be loaded onto a computer for analysis. The network data collector&#39;s memory is erased and a new set of data collection begins. This type of system is used to monitor buildings and factories. An example of this type of instrument is Wizard from Dickson. While useful for some tasks, the system has drawbacks. It requires a personal computer to display the results, so it is cumbersome to move around a building. The sensor modules are shaped for mounting on a desk or file cabinet or other flat place, but are not convenient for air diffusers and pipes. 
         [0040]    In a quite different industry, medical monitoring of vital signs, wearable wireless instruments have appeared. These collect measurements such as blood pressure or pulse rate and wirelessly transmit the results to a nearby data collector or to the wrist of the user. From there results can be viewed or sent to a monitoring system for review or alarm. A related module might sound an alarm to the person wearing the sensors to alert them to excessively high blood pressure or similar problem. However, this type of instrument is not useful for finding and fixing HVAC problems, because it does not provide for remote sensors measuring environmental conditions. 
         [0041]    Another interesting wireless application is wrist-mounted displays for runners and other athletes that show data from sensors mounted in their shoes or on their bodies to provide a measure of their performance. These systems lack remote sensors that measure environmental parameters, as well as other features that are applicable to HVAC and other industrial applications. 
       Problem Summary 
       [0042]    To summarize the general problems with traditional instruments and methods, they limit the productivity of technicians by being heavy, cumbersome, by not measuring all of the required parameters simultaneously, by restricting the availability of measurement data among team members, and by forcing repeated movement between the points of cause and effect. Measurement procedures take much longer than desirable. Time is wasted. These problems lead to short cuts by technicians, which in turn product inaccurate or misleading measurements that have little credibility among industry peers. 
         [0043]    Accordingly, improved apparatus, methods, and systems for measurement of environmental parameters are desired. 
       SUMMARY OF THE INVENTION 
       [0044]    The present invention generally relates to an apparatus, system, and methods for measuring environmental characteristics of fluids, such as air and water. While the ways in which the invention address the various drawbacks of the prior art are described in more detail below, in general, the apparatus, system, and methods collect desired environmental measurements from many locations and conveniently present the desired measurement results in real-time. 
         [0045]    In accordance with various exemplary embodiments, a system for wireless measurements comprises a variety of sensors to make in-situ measurements and transmit the results to the user where they are displayed and stored, e.g., via wearable modules, to free the hands of the user to make control adjustments and deal with tools. 
         [0046]    In accordance with various exemplary embodiments, a system comprises applications-specific wireless sensing modules for accurate, in-situ measurement of building parameters, and wearable instrument components for real-time access via visual display and/or audible words, by technicians for beneficial use at the location of adjustment and control. The present invention is an instrumentation system of distributed modules with various functions. Each module may be specially designed for a specific HVAC-related measurement function. Communication between modules may be via wire and/or RF wireless. 
         [0047]    Unexpected benefits are derived from distributing the functional aspects of a measurement system to the location where they are best performed. Sensing and measurement may be done on a continuous schedule at the point of interest, in-situ, and does not burden the technician after placement. Results arrive regularly to a location where a technician can easily view it and act on it. Different results from different locations are presented together to improve understanding of the environment and quicker technician actions. Results are shared among all team members for optimum efficiency, and team members may communicate via the optional integrated walkie-talkie feature. 
         [0048]    Improvements include better safety, reduced technician time, better accuracy, and less expensive instrumentation. 
         [0049]    Exemplary system communication and control modules include:
       Control   Display   Head mount display   Head mount audio   Thumbswitch   Repeater   Computer/PDA interface   Web access       
 
         [0058]    Sensor modules include the following types:
       Temperature types for air, water, and surfaces.   Humidity types.   Pressure types for air.   Pressure types for water   Air velocity   Airflow   CO concentration   CO2 concentration   Light intensity   RPM for fans/motors   Inclinometers for damper vane position/angle   Instrument interface modules provide interfaces to existing instruments and sensors such as electric utility meters and ultrasonic flow meters using one or more of these methods:   Digital communication stream   Pulse counter   Analog 4-20 mA current loop.   Analog voltage 0-5 v and 0-10 v.       
 
         [0075]    The present invention includes this new apparatus:
       Light-weight capture hood.       
 
         [0077]    The various embodiments provide improved methods:
       Adjustment of dampers for adequate ventilation.   Adjustment of duct static pressure setpoint.   Duct velocity traverse.   Water-side balancing.   Adjustment of Room-to-Room pressures.   Proportional balance.       
 
         [0084]    The various embodiments provide a technician with freedom of movement while viewing measurement data on his wrist. He can see the result of his adjustments in real-time and store measurement values while moving around. 
         [0085]    A display format is provided to compare and contrast two or more different measurements from different locations. A personal computer may serve as a control module with an appropriate communication module plugged into its port. 
         [0086]    The present invention allows multiple team members to share measurement results via a wearable module, which promotes better teamwork and higher productivity. Optional walkie-talkies are built into the control modules to provide voice communication via the same communication method used for measurement data. 
         [0087]    These system capabilities make possible new, better methods for industrial repairs and adjustments. For instance, they eliminate the back-and-forth nature of many industrial operations where the point of interest is different from the point of control. Instead of a long cycle measurement/adjustment/measurement/etc., a real-time stream of measurements is available at the point where the adjustment is being made, saving time and facilitating a more precise final result. 
         [0088]    The distributed nature of the instrument in the present invention makes it possible for a technician to make the necessary measurements at the location of interest, transmit the measurements quickly to the location where they are most needed for decisions and adjustments, which may be a few feet or hundreds of feet away. The measurement results can be displayed on a wrist-mounted module, a head-mounted module for heads-up viewing, or annunciated in the user&#39;s ear. The user&#39;s hands during this process are free for tasks instead of being occupied by instruments. 
         [0089]    Various embodiments of the present invention combine two operating modes that were previously only available in different instruments. One is a diagnostic or debugging mode used by a technician to promptly discover and fix problems. The other is a monitoring or datalogging mode which collects measurements regularly from distributed sensors over a period of hours, days, or weeks. The data is analyzed later, usually plotted against time to show relationships between events. A related and unique capability is that the present invention allows a mobile module to display the results in a diagnostic mode from sensors that are also at the same time part of a datalogging network. 
         [0090]    The various embodiments also make existing instruments more useful in several ways. Each result may be sent from the location of measurement to the location where an adjustment is necessary. The control module provides a very large memory for storing measurements and provides statistics that are often missing in other instruments. Measurements may be stored and compared along the same timeline as measurements from different instruments. The measurement data can be shared by multiple technicians in real-time. 
         [0091]    Sensor modules are sensing instrument probes that measure environmental parameters such as temperature, humidity, and pressure. Sensor modules are provided in accordance with various aspects of the present invention. Exemplary sensor modules include handles and means of attachment to industrial equipment so they do not have to be held by a technician when readings are being taken. Each of the sensor modules is designed to be small and easy to handle and be placed at a particular point of interest where the best accuracy can be obtained, and they can then be left, in-situ, performing continuous measurements that are sent to the technician wirelessly. They are designed to dramatically speed up a particular type of measurement and improve accuracy. They are designed to overcome the problems inherent in current industry practice as described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0092]    The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements and wherein: 
           [0093]      FIG. 1  illustrates the system form in accordance with exemplary embodiments; 
           [0094]      FIGS. 2A and 2B  illustrates the wearable control module in accordance with exemplary embodiments; 
           [0095]      FIG. 3  illustrates the thumbswitch in accordance with exemplary embodiments; 
           [0096]      FIGS. 4A ,  4 B,  4 C illustrate head-mountable communication in accordance with exemplary embodiments; 
           [0097]      FIGS. 5A ,  5 B,  5 C illustrate the use of repeater modules for extending the usable system range in accordance with exemplary embodiments; 
           [0098]      FIGS. 6A ,  6 B illustrate repeater modules in accordance with exemplary embodiments; 
           [0099]      FIGS. 7A ,  7 B illustrate an application for a system of temperature and humidity modules in accordance with exemplary embodiments; 
           [0100]      FIGS. 8A ,  8 B,  8 C,  8 D,  8 E,  8 F,  8 G illustrate a multitude of measurement result display formats in accordance with exemplary embodiments; 
           [0101]      FIGS. 9A ,  9 B,  9 C,  9 D,  9 E illustrate some types of temperature modules in accordance with exemplary embodiments; 
           [0102]      FIGS. 10A ,  10 B,  10 C,  10 D illustrate humidity sensor modules and related display formats in accordance with exemplary embodiments; 
           [0103]      FIGS. 11A ,  11 B,  11 C,  11 D illustrate differential air pressure sensors in accordance with exemplary embodiments; 
           [0104]      FIG. 12  illustrates measurement of water pressure and temperature in accordance with exemplary embodiments; 
           [0105]      FIG. 13  illustrates areas of different pressures in a cleanroom; 
           [0106]      FIG. 14  illustrates a system of duct air sensors in accordance with exemplary embodiments; 
           [0107]      FIG. 15  illustrates a variety of informational displays in accordance with exemplary embodiments; 
           [0108]      FIG. 16  illustrates duct air measurements in accordance with exemplary embodiments; 
           [0109]      FIG. 17  illustrates air measurement and adjustment in accordance with exemplary embodiments; 
           [0110]      FIG. 18  illustrates air measurement in accordance with exemplary embodiments; 
           [0111]      FIG. 19  illustrates air measurement in accordance with exemplary embodiments; and 
           [0112]      FIGS. 20A ,  20 B,  20 C illustrate sensor modules and instrument interface modules in accordance with exemplary embodiments. 
       
    
    
       [0113]    It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of illustrated embodiments of the present invention. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0114]    The description of exemplary embodiments of the present invention provided below is merely exemplary and is intended for purposes of illustration only; the following description is not intended to limit the scope of the invention disclosed herein. Moreover, recitation of multiple embodiments having stated features is not intended to exclude other embodiments having additional features or other embodiments incorporating different combinations of the stated features. 
         [0115]    The apparatus, system, and methods of the present disclosure may be used for a variety of applications in HVAC, safety, lighting, and security systems in buildings and factories, including such applications as duct static pressure adjustment, airflow damper adjustment, room-to-room pressure adjustments, water side HVAC balancing, HVAC coil efficiency measurements, and the like. Included are measurements for immediate use as well as datalogging measurements at regular intervals over an extended period of time. As set forth in more detail below, the exemplary system and methods are generally easier to use, less time consuming, and require fewer and less expensive instruments compared to traditional systems and methods that provide similar functions. 
         [0116]      FIG. 1  illustrates a system  100  in accordance with exemplary aspects of the invention. System  100  includes modules of various types for measuring environmental parameters, and then viewing, storing, and sharing the measurement results. The modules of system  100  have wired and/or wireless means of communicating information, commands, and measurement results. Illustrated system  100  includes control module  110 , optional repeater module  112 , optional sensor interface module  172 , and a multitude of sensor modules described below, one or more of which may optionally be present in system  100 . Illustrated system  100  also includes means for enhancing the usability of control module  110 , including wrist display module  120 , head-mounted display  121 , audio module  122 , thumbswitch  111 , computer interface  131 , PDA interface  134 , and cellular data module  133 . Use of system  100  improves user productivity in many ways, including: by allowing users to take measurements while using their hands for other tasks; allowing users to compare results from multiple locations concurrently; eliminating back-and-forth motion for repetitive measurements, facilitating information sharing among coworkers; easier set-up for complex and cumbersome measurements; facilitating more accurate results by maintaining measurement probes in-situ at the location of interest. 
         [0117]    Users may include team leader  101  and associate  102 . Users  101  and  102  may have placed one or more sensor modules  151 ,  152 ,  153 ,  154 ,  155 ,  156 ,  157 ,  161 ,  162 ,  163 ,  164 ,  165  in particular locations to make specific measurements required for industrial operations. Measurement results from sensor modules  151 ,  152 ,  153 ,  154 ,  155 ,  156 ,  157 ,  161 ,  162 ,  163 ,  164 ,  165  are transmitted to control module  110 . Not part of the present invention are traditional instruments such as, e.g., water volumetric flow meter  171 . However, the present invention includes interface module  172 , which may connect to an existing data output port of flow meter  171 , if present. Interface module  172  may transmit measurements wirelessly to control module  110 . 
         [0118]    Control module  110  establishes and maintains the network by which all system modules communicate. Control module  110  may also have other functions, including display and storage of measurement data. Repeater module  112  has the function of a wireless signal repeater. Repeater module  112  is optional in system  100 . When the distance between modules becomes too great for effective wireless transmission, repeater module  112  may be placed midway between the modules to allow signals to “hop”. Signals from the transmitter are first received by repeater module  112 , which in turn transmits over the now reduced distance to the receiver. 
         [0119]    Control module  110  is operated via keys, buttons, and/or switches on control module  110 . Control module  110  may also execute certain commands which are entered by user  101  via buttons, keys, or switches on thumbswitch module  111 . Control module  110  may also execute certain commands which are entered by user  101  via microphone  123  on audio module  122 . The ability to input commands verbally or via thumb movements allows user  101  to use his hands for something else while still making and/or storing measurements. 
         [0120]    Also important to productivity is the ability to see or hear results without the need to use hands or arms. Control module  110  on user  101  may transmit information, including measurement results, to wrist display module  120  on user  102 , and/or heads-up display module  121 , and/or audio earphones  124  on audio module  122 . Time and effort are saved by the ability of users  101  and  102  to both see the same measurement results at the same time despite their different locations. Other activities, including using hands for equipment repair and/or adjustment, may proceed while measurement results continue to arrive in real time. 
         [0121]    Voice communication between team members in different locations may improve productivity. Control module  110  on user  101  and display module  120  on user  102  may include microphones and speakers and the software and hardware means to transmit voice via the same RF waves that communicate measurement results. This may eliminate the need to communicate information or instructions by walking to conference, by walkie-talkie instruments, or by cell phones. Headphone module  122  on user  101 , with microphone  123  and earphones  124 , may also be used to for voice communication, with transmission controlled by control module  110 . 
         [0122]    Productivity may be improved when information can be reviewed from a great distance. For example, a manager at a home office may be able to detect an HVAC problem by viewing measurement results at a remote location in real-time, and promptly give appropriate instructions. Building commissioners often share measurement information with colleagues across the country to compare results from similar buildings. System  100  provides means for transmission of information to remote servers  143 , which may be accessed via the Internet. One way is for the control module  110  to transmit to cellular data module  133 , which in turn has a connection  141  through the cellular telephone system to a remote server. A second way is for control module  110  to transmit to computer  130  via i/o module  131 . Computer  130  may be directly connected to the Internet via a cable  141  or via a Wi-Fi connection  142 , both of which offer means of transmitting information from system of modules  100  to a remote server for world-wide viewing. A third way of storing information at one or more remote servers is via a PDA  135  controlled by user  101 . Data may be collected by PDA  135 . Once stored in PDA  135 , information may be transmitted to a remote server via Wi-Fi or via the cellular data network. 
       Module Components and Design Features 
       [0123]    Exemplary electronic modules of the present invention include electronic assemblies built from customized printed circuit boards with microprocessor-based control circuits. The modules may be in relatively small enclosures of an appropriate size and shape for a specific system function. Enclosures may be a standard product purchased from a supplier such as TEKO, or may be built to a custom design. Holes in the enclosures may be drilled to provide access for connectors, keypad, display, and mounting means such as a strap. 
         [0124]    The contents of system  100  modules may include one or more of these electronic hardware and software feature sets:
       Embedded controller for general functions within a module.   LED&#39;s and/or other display devices and related display control.   Sensing electronics for analog or digital inputs.   Keypad and On/Off switch and other switches, keys, or buttons.   Battery and/or transformer.   Audio electronics, microphone, speaker(s), drivers.   Connectors for power, signals.   Wired signal transmission drivers and protocols.   Wireless transmission drivers and protocols, including RF point-to-point, RF multipoint, RF ZigBee, Bluetooth, Wi-Fi, GPRS and/or other cellular data protocol.   Antenna(s) appropriate for the extant protocols and frequency channel.       
 
         [0135]    System  100  may include a wireless sensor network (WSN). WSN&#39;s are established using standard hardware and software, included in every node of the network. For example, a ZigBit is a communications component supplied by Atmel with related software for installation in multiple modules. The modules then have the capability to create and maintain a WSN based on the ZigBee Alliance protocol, which is an open standard. ZigBee uses an international standard 802.15.4 protocol and standard ISM frequency ranges. 
         [0136]      FIGS. 2A ,  2 B illustrate an exemplary wearable control module  110 . Loops  201  support a wrist strap  204  or a spring bracket for mounting on other convenient apparatus. Control module  110  may also be mounted via magnets, Velcro, tape, or other means to an HVAC duct, pipe, rod, wire, cable, or other structure where convenient for the user. Keypad  202  may be used to control the display, storage of measurement results in memory with time and date, and the network. Antenna  205  may be a relatively long or relatively short dipole antenna that protrudes from the enclosure, or it may be another type of antenna installed internal to the enclosure. Connectors  206  may be electrical ports for communication and/or power. Display  203  can show the results from multiple sensors from multiple locations. A variety of display formats are provided for specific applications, allowing the user to compare and contrast different conditions in different locations. Real-time feedback from adjustments of environmental controls is very beneficial to productivity. 
         [0137]    System  100  includes operating modes that were previously only available in different instruments. Control module  110  may operate in a diagnostic or debugging mode to discover and promptly fix problems. Control module  110  may also be used as a datalogger, collecting measurements regularly from multiple distributed sensors over a period of hours, days, or weeks. The data may analyzed, for example by plotting the information against time to show relationships between events. Control module  110  can operate in the debug mode or the data-logging mode or both at the same time. Two control modules  110  can operate at the same time in the same network, one operating in debug mode and one in data-logging mode. 
         [0138]    Multiple control modules  110  can operate in the same environment with different sets of network modules. Unique addresses prevent communication between the different networks. 
       Control Module Display Formats 
       [0139]    Control module  110  includes the ability to display information in a wide variety of formats, depending on the desires of the user. Control module  110  includes means for displaying and storing measurement results from multiple sensor modules from multiple locations.  FIGS. 8A ,  8 B,  8 C,  8 D,  8 E,  8 F,  8 G illustrate some of the formats available to users. Other display formats may be configured for specific measurement applications, as discussed below. In  FIG. 8A , large characters facilitate viewing from a distance. In  FIG. 8B , a current reading is displayed in large characters at the upper left, while smaller characters at the right list the three prior readings. This gives an indication of the trend of the parameter. In  FIG. 8C , a current reading is displayed in large characters at the upper left. At the lower left are shown the current memory group selected, AA, and the sequence number of the last value stored,  123 . On the right are listed statistics for the current memory group AA, average, maximum, and minimum. In  FIG. 8D , results from two different temperature sensor modules, S 1  and S 2 , are displayed side-by-side. In  FIG. 8E , results from two different sensor modules are displayed side-by-side. This type of sensor module supplies both a temperature and a relative humidity. The user can therefore compare four concurrent measurements from two different locations. In  FIG. 8F , concurrent results are displayed from four different sensors in four different locations. Sensor module S 1  is measuring temperature in degrees Fahrenheit. S 2  is measuring barometric pressure in inches of mercury, S 3  is measuring percent relative humidity, and S 4  is measuring differential air pressure in inches of water column. In  FIG. 8G , a list of data-logged measurements is shown with columns for record number, sensor number, time of record, value, and units. The date of the reading is displayed above. 
       Control Module Construction 
       [0140]    Control module  110  may have a keypad that is a membrane switch assembly as illustrated in  FIG. 2 . Control module  110  may be powered by a rechargeable lithium-Ion or lithium-polymer battery, which is recharged through a mini-USB port. 
         [0141]    Control module  110  may have an LCD display with LED backlight for good visibility in dark environments, embedded controller, memories, real-time clock, audio codec, speaker, microphone, connectors, keypad, and other electronic components. Control module  110  displays the results which are received wirelessly at specified intervals from various sensor modules. Control module  110  may have a provision for storing measurements by pressing a key. Control module  110  manages the wireless and or wired communications of system  100 . The present invention includes programmed features to tailor the network to the environment of field users, who may not be trained in networking. Features included for network durability and practicality in industrial environments include displays of status and problem alerts, and a “heartbeat” system in which each module regularly reports its status to control module  110 . 
         [0142]    Control module  110  may use an ATMega256 microcontroller by Atmel, but other similar microcontrollers, either 8-, 16-, or 32-bit, could have been chosen. Standard C programming techniques were used to produce the controlling program, using standard development software from, for example, Atmel. The microcontroller of control module  110  performs these functions:
       manages power-on and power-off sequences   monitors the keypad for user inputs, the real-time clock, and the battery status   feeds data and text to the display   transfers data to and from the wireless network module   manages the audio codec   manages the mini-USB port for recharging the battery   manages the mini-USB port for transmissions to and from a fixed or mobile computer.   manages the Wi-Fi or other wireless port for transmissions to and from a fixed or mobile computer.   manages the wired or wireless port for transmissions to and from the Web Access Module.   manages the SD data port for storing data on a tiny SD-format memory disk.       
 
       Alternate Embodiments 
       [0153]    Control module  110  features may be implemented by a PDA or smartphone or mobile computer to which is attached a network control module. 
       Thumbswitch Module 
       [0154]      FIG. 3  illustrates thumbswitch  111 , an optional module in system  100 , which can be worn on a finger via stretchable fabric loop  301 . If the user is holding tools or otherwise can&#39;t move his arm to touch the keypad  202  of wearable control module  110  of  FIG. 2A , he can effect a subset of keypress commands by pressing one or more buttons  302  on thumbswitch  111  as illustrated in  FIG. 3 . Examples of commands executed by wearable control module  110  but initiated via thumbswitch buttons  302  include storing a reading and changing a display format. One or more status indicators  303  may be present. Thumbswitch  111  may fit in different places on different fingers, giving a user the flexibility to hold tools of different shapes while maintaining the ability to press buttons  302 . Wearable thumbswitch  111 , together with wearable control module  110 , and sensor modules that measure in-situ and need not be held, allow users the freedom to perform tasks with their hands while measuring and monitoring the environment. 
       Optional Modules for Disseminating Information 
       [0155]      FIGS. 4A ,  4 B,  4 C illustrate head-mountable communication and control apparatus.  FIG. 4A  illustrates some exemplary details of head-mountable display module  121  from  FIG. 1 . Small display  401  is positioned in similar fashion to rear-view mirrors worn by bicyclists. Clamp  404  grips a cap, and supports small rod  403 , from which display  401  is suspended. Images may be provided by module  402 , which may be optionally attached to the back of a cap, attached to the back of a collar, placed in a breast pocket, or placed in some other location. Communication with control module  110  may be wired or wireless. 
         [0156]      FIG. 4B  illustrates exemplary details of audio module  122  from  FIG. 1 . Headphone and microphone arrangement  411  provide audio content such as measurement results and verbal messages from coworkers. Spoken commands may control operation of control module  110 .  FIG. 4C  illustrates exemplary detail of audio module  122  from  FIG. 1 . Common ear bud  422  may use Bluetooth or Wi-Fi or other protocol for communication with control module  110 . 
         [0157]    The electronics of head-mounted modules  121  and  122  may be battery powered. Alternatively, the battery in control module  110  in  FIG. 1  and  FIG. 2  may feed the other components via a wire. Alternatively batteries may be integrated with the audio and/or video electronics modules, or external batteries may be located in a module worn on the user&#39;s belt, in his shirt pocket, clipped to the back of his shirt collar, or clipped to the back of his ball cap or helmet. Commands, measurement results, and information may be transmitted from module to module via wire or via wireless RF. 
       Optional Repeater Module 
       [0158]    Remote sensor modules may communicate with a control module  110  in a variety of ways. Some of these are illustrated in  FIGS. 5A ,  5 B,  5 C.  FIG. 5A  illustrates a sensor module  151  in wireless communication with control module  110  from  FIG. 1  and  FIGS. 2A ,  2 B. Control module  110  maintains a record of a unique identification number for sensor module  151 . Wireless communication parameters such as signal strength and frequency are managed cooperatively by integrated hardware and software. Sensor module  151  makes regular measurements and transmits results to control module  110 . Control module  110  can display the results for the user without storing them, or the user may cause the results to be stored with the value, units, sensor ID, time, and date. The user may cause the results to be stored without viewing them. The user may change the schedule of measurement. When sensor module  151  is not measuring or transmitting, it may put most of its electronic components into a sleep mode which uses very little power, such that a battery in sensor module  151  may have a relatively long useful life. 
         [0159]    As illustrated in  FIG. 5B  the user may require that sensor module  151  be placed at such a distance from control module  110  that wireless signals are too weak to maintain effective communication. In this situation control module  110  will display an alert to the user, who may then deploy repeater module  112  at a location somewhere between sensor module  151  and control module  110 . Repeater module will be at an effective distance to receive transmissions of information from sensor module  151  and will retransmit said information, which control module  110  is near enough to properly receive. 
         [0160]      FIG. 5C  illustrates that multiple repeater modules  112  may be used to extend the effective range between sensor module  151  and control module  110 .  5 C also illustrates that control module  110  may maintain communication with multiple sensor modules  151  at the same time, including some that are in direct communication as well as those whose messages are being repeated. 
         [0161]      FIGS. 6A ,  6 B illustrate two exemplary configurations for repeater modules. In  FIG. 6A , repeater module  601  includes an On/Off switch  602  and one or more indicator lights  603 . Repeater module  601  includes a relatively small battery and a relatively small antenna, with a correspondingly short range, relatively speaking. In  FIG. 6B , repeater module  611  includes a large antenna  612  with a correspondingly longer range, relatively speaking. A large battery is included, as well as a transformer and wall electrical outlet prongs  613  for recharging the battery and/or operating while attached to mains power. A port  614  is included for attaching a cable for information transfer and/or powering from an external battery, solar panel, or other power source. A sensor  615  is included to allow repeater module  611  to measure and transmit environmental conditions from its immediate area, in addition to performing its function as repeater. A display  616  is included so a user may view status and other information. Buttons and/or keys and/or switches  617  are included to allow setup and manipulation of included functions, in addition to On/Off switch  618  and indicators  619 . 
       Sensor Modules—Common 
       [0162]    Sensor modules are sensing instrument probes that measure environmental parameters such as temperature, humidity, and pressure. The present invention includes many different types of sensor modules to address a multitude of HVAC applications. One or more sensor modules may optionally be present in an operating system  100 . The present invention offers a common platform for users and reduces the number of different instruments required for HVAC applications, saving money and time. 
         [0163]      FIG. 1  illustrates a multitude of sensor modules attached to various HVAC fixtures where users may require measurements for solving problems and/or adjusting equipment. For example, sensor modules  151 ,  152 , and  153  are placed in different locations of interest. Sensor module  151  has a shaft type of sensing probe that penetrates a small hole in an air duct and measures temperature. Sensor module  152  has a button shape for measuring the surface temperature of, e.g., water pipes. Sensor module  153  measures temperature and humidity, and has a shape and features to allow users to easily attach it to, e.g., air supply ceiling diffusers. Sensor modules  151 ,  152 , 153 , like other sensor modules in the present invention described below, may be designed to be relatively small and easy to place at a particular point of interest in HVAC applications. Sensor modules may be designed to remain at the point of interest, in-situ, and continue measuring and transmitting results to a location convenient to the user. Sensor modules may have unique handles and means of attachment to industrial equipment so they do not have to be held by a technician when readings are being taken. When using sensor modules instead of traditional handheld meters, users need not make repeated trips to a point of interest for follow-up measurements. 
         [0164]    As illustrated in  FIG. 1 , sensor modules  151 - 157 ,  161 - 165  may be placed in or on air ducts, air diffusers, water pipes, condenser coils, walls, floors, ceilings, desktops, or many other places in buildings and factories. It is the combination of size, shape, accessories (magnets, rings, clips, Velcro, adhesive dots, etc.), and the convenient communications link, usually wireless, to the Control Module  110 , that make the sensor modules of the present invention uniquely suitable for industrial measurement applications. When used in a system  100 , sensor modules  151 ,  152 , and  153 , as well as other sensor modules described below, reduce the time required for industrial procedures and improve accuracy and safety. 
         [0165]    System  100  may include wireless sensor modules for these HVAC applications:
       Insertion air temperature.   Surface temperature.   Average temperature of ducts and mixing chambers.   Insertion humidity probe.   Fluid pressure and temperature in pipes.   Differential Water Pressure Sensor Module   Differential air pressure module with unique door mount.   Velocity Sensor Module.   Airflow probe for inlets and outlets.   Other sensor modules for CO2 concentration, CO concentration, light intensity, inclinometer, motor/fan rotor speed in RPM, switch status (open/closed).       
 
         [0176]    System  100  of  FIG. 1  includes instrument interface module  172  which allow existing meters and sensors to be interfaced to control module  110 :
       Instrument interface for instruments which have digital output ports, such as these instruments popular in HVAC applications: Shortridge AirData Multimeter™ series; TSI/Alnor EBT 720 series; Kanomax Climomaster A5xx series; other instruments with digital outputs.   Instrument interface for third-party instruments and sensors which feature standard analog outputs formats: 4-20 mA; 0-to-5 volts; 0-to-10 volts.       
 
       Sensor Module Construction 
       [0179]    Sensor modules, including sensor modules  151 - 156  and  161 - 165 , may include: a custom printed circuit board, one or more status LED&#39;s, sensor or sensor connector, battery, communication circuitry. One or more microcontrollers are programmed to control the LED indicator(s), power on and power-off sequences, battery power monitoring, and sensor interface. Sensor modules may use primary or rechargeable batteries, and may also provide means for mains power and/or external battery power. Sensor modules include means for attaching to key locations of interest and remain in-situ while delivering a stream of regular measurements. 
       Temperature Sensor Module 
       [0180]      FIGS. 9A ,  9 B,  9 C,  9 D,  9 E illustrate illustrates a temperature sensor module  901 , including a sensing and radio electronics part  902  and a connected sensing probe  911  or  912  or  913 . Sensor probe  911  has a sensing element  921  at the end of a stiff shaft. Sensor probe  912  has a flexible lead attached to a button-style sensing bulb  922 . Sensor probe  913 , for applications that require the average temperature in a space, has a thermally conductive lead in which are located one or more temperature sensor elements  923 . Each sensing probe  911 ,  912 ,  913  may be connected to sensor module  901 . Sensor module  901  includes an On/Off switch and one or more LED&#39;s or displays. Sensor module  901  may include magnet  931  and/or magnet  932  applied to one or more facets of the module for attaching to ferrous surfaces. Facet  933  may have a surface appropriate for taping or attaching or affixing sensor module  901  to a non-ferrous surface, using, for example, tape, Velcro, or other known means for attachment. Ring  934  may be present to allow clipping or hanging from lines or pipes or other available structure. 
         [0181]      FIG. 7  illustrates some applications of temperature sensor module  901 . Illustrated is a simplified model of an HVAC system serving part of a building. Sensor module  901  with sensor probe  911  sits on a table to measure room temperature. Sensor module  901  with sensor probe  911  uses magnet  931  to attach to ferrous fixtures at ceiling locations  702  and  703 . Location  702  represents supply air temperature entering room  708 , while location  703  measures the temperature of room air as it passes through a return air grille and enters a return air duct. A sensor of type  901  is located at  719  to measure return air temperature and another at location  710  measures fresh outside air being brought in to ventilate the building and replace stale air. In mixed air chamber  713 , two air streams collide in a turbulent environment, where temperature probe  913 , is used to measure the average air temperature. The mixed air exits through filter  714 . Fan  715  propels the air past coil  716  and into the supply air duct. The temperature of the water in the coil pipe is approximated by the sensing probe  922 , which is held against the pipe with tape or strap. Ring  934  provides means to hang the sensor module  901  near the location to be measured. 
       Method for Measuring Mixed Air Proportions 
       [0182]    HVAC industry rules require a certain amount of fresh outside air for each square foot of occupied space. An air balancer must supply just enough, but not too much, outside air. Dampers  711  and  712 , along with fan speeds, are varied to achieve the necessary outside air. Air balancers make a calculation to determine outside air volume by comparing the respective temperatures of supply air, return air, outside air, and mixed air. Industry practice is to measure each location ( 709 ,  710 ,  713 ,  706 ), then adjust the dampers, then measure again, repeating this cycle until the required relationships of temperatures are achieved. This is an iterative process that is time consuming. The current invention allows sensors to be placed as described above. As better seen in  FIG. 7B  module  110  provides four continuous readings from four different locations in the format shown in  FIG. 7(   b ): return air temperature  721 , outside air temperature  722 , mixed air temperature  723 , and supply air temperature  724  (after being cooled by coil  716 ). With this improved method, the required adjustments can be made relatively quickly, reducing manpower and shortening schedules. 
         [0183]    In accordance with additional embodiments of the invention, a method of measuring mixed air proportions includes the steps of:
       deploy temperature sensor in the air mixing chamber;   deploy temperature sensor in the outside air duct;   deploy temperature sensor in the return air duct;   deploy temperature sensor in the supply air duct;   display results from four sensor modules concurrently on control module  110 ;   calculate the proportion of supply air that is outside air;   calculate the outside air volume;   calculate the desired outside air volume based on occupancy, usage type, etc.;   compare the actual outside air volume to the desired outside air volume;   adjust outside air damper and return air damper while observing the changes in measured air temperature on control module  110 .       
 
         [0194]    Traditional methods require many iterations of measurements, accompanied by a lot of back and forth movement. The ability to deploy sensor modules for continuous measurements saves a lot of time and effort. Also, because it is relatively easy to achieve a precise outcome, users are less likely to take shortcuts which may retain an undesirable level of outside air. 
       Humidity Sensor Module 
       [0195]      FIGS. 10A ,  10 B illustrate exemplary configurations of humidity modules that are part of system  100 . Sensor module  1001  includes sensing probe  1002 , which can be used with or without extension rod  1003 . The longer configuration is useful for placing the sensing element  1004  at a particular location in large ducts. Sensor module  1001  with sensing element  1004  measures temperature as well as humidity.  FIG. 10C  illustrates four different exemplary results available from one measurement: relative humidity percent  1011 ; dry bulb temperature  1012 ; wet bulb temperature  1013 ; dew point temperature  1014 . Optional results not shown include grains of water per cubic foot.  FIG. 10D  illustrates exemplary displays from two humidity modules in different locations. A user may view for comparison these results: RH from S- 1   1021 ; dry bulb temperature from S- 1   1022 ; RH from S- 2   1031 ; dry bulb temperature from S- 2   1032 . 
       Differential Air Pressure Sensor Module 
       [0196]      FIGS. 11A ,  11 B,  11 C,  11 D illustrate an exemplary of a differential air pressure sensor module.  FIG. 11(   a ) illustrates a version of the sensor module with two ports, and  FIG. 11(   b ) illustrates a four-port version. The pressure between the ports is measured and transmitted to control module  110 . 
         [0197]    Air pressures are involved in a multitude of HVAC applications, including duct static pressure and velocity pressure. Duct static pressure is the difference between the pressure of duct air and room air. Velocity pressure is related to air velocity. It is measured as the difference between two types of orifices on the probe.  FIG. 11C  illustrates both of these measurements. 
         [0198]      FIG. 11C  illustrates differential pressure sensor module  1101  attached via included magnet  1113 , shown in  FIG. 11A , to the side of an air duct. An industry standard probe  1132 , a static tip, is inserted through a hole in the wall of duct  1131  and oriented into the airstream such that the static pressure of the duct is present at probe output port  1134 . A flexible hose  1133  is connected between port  1134  and sensor module port  1111 . Sensor module port  1112  is exposed to ambient air. The sensor module then measures the difference between the pressure of the air in the duct and the pressure of the air outside the duct. The result, e.g., 1.25 inches of water column, is sent wirelessly to control module  110 . 
         [0199]    Also in  FIG. 11C , differential pressure sensor module  1102 , with four ports, is attached via included magnets to the side of air duct  1131 . An industry standard probe  1141 , a Pitot tube, is inserted through a hole in the wall of duct  1131  and oriented into the airstream. Pitot tube  1141  has two output ports, and there are two differential pressures typically of interest to users. Connected to the static pressure port is flexible hose  1142 , which is connected to sensor module  1102  via ports  1121  and  1123 . Another flexible hose  1143  is connected to sensor module  1102  port  1124 . In this configuration, the sensor module transmits two results of interest to control module  110 . Duct static pressure is the difference between sensor module ports  1121  and  1122 . Velocity pressure is the difference between sensor module ports  1123  and  1124 . 
         [0200]    Differential pressure module s  1101  and  1102  are useful in several applications, including setting duct pressure, setting room-to-room pressure, setting occupied space pressure vs. outside air, fume hoods, biosafety cabinets, and others. Most commercial and industrial buildings are specified to have a slightly positive pressure to preventingress of outside air, humidity, leaves, and bugs (think restaurant dining areas). The pressure drop across filters is a key measure of the cleanliness of filters. The present invention is designed to quickly and easily detect problems in these areas and alert a technician, building manager, or restaurant owner. The present invention provides results of pressure measurements from multiple locations to be reviewed and compared concurrently, which reduces the time involved in certain procedures. An exemplary application is described below. 
       Application: Measuring and Adjusting Room-to-Room Differential Pressures 
       [0201]    The innovative capabilities of the present invention are especially important for cleanroom applications such as semiconductors, pharmaceutical, and hospitals, where multiple related pressures are specified.  FIG. 13  illustrates a wafer fabrication facility  1301  with outside walls  1302 , an exterior entry  1303 , corridor  1304 , suit-up room  1305 , air wash  1306 , general operations area  1307 , and mini-environment for special processes  1308 . The requirement for air cleanliness depends on the nature of the area. Pressure differences are one of the primary methods of controlling the direction and degree of contaminant movement. That is, a space with a great need for cleanliness will be specified to have a higher pressure than adjacent areas. Typical room-to-room pressure differences are maintained between 0.03 inches of water column and 0.06 inches of water column. For the building illustrated in  FIG. 13 , there may be a specification for these pressure differences:
       R 1304  to  1303 : 0.02 in. wc.   R 1305  to  1304 : 0.03 in. wc.   R 1306  to  1305 : 0.04 in. wc.   R 1307  to  1306 : 0.05 in. wc.   R 1308  to  1307 : 0.05 in. wc.       
 
         [0207]    Pressure differences are created by adjusting fan speeds and dampers to adjust the volume of supply air and return air for each space. The fans and dampers may be located at quite some distance from the points being measured. The pressures are interrelated, so adjusting one fan or damper can affect two or more room-to-room pressures. A conventional differential pressure sensor, usually held near a door by a technician using two hands, can measure only one or two differential pressures at a time, and the result is nowhere near the point of control, the fan or damper. The user records the measurement, moves to the point of control, makes and adjustment, and returns to make another measurement. The HVAC system is often organized such that the room characteristics are interrelated. An adjustment of one fan may affect two or three rooms, causing rooms that were in spec to go out of spec. Then the process begins again. The current industry method involves a long, drawn-out series of measurements and adjustments. 
         [0208]    System  100  allows multiple sensors to be placed where necessary. The room-to-room pressure measurements are continuously transmitted wirelessly to the wrist of the technician, who can display and store two or more measurements at the same time. In most cleanroom buildings the technician has access to the control elements from an interstitial level above the cleanrooms themselves. With the information provided by the present invention, he can quickly achieve all of the specified pressure set-points, saving a lot of time and effort. 
       Method of Measuring Room-to-Room Pressures 
       [0209]    In accordance with additional embodiments of the invention, a method of measuring a multitude of room-to-room differential pressures concurrently includes the steps of:
       deploy differential pressure sensor modules to each location of interest;   link each sensor module with the control module;   deploy repeater module(s) if necessary for increased range;   select an appropriate display format on control module;   observe differential pressure measurements in real time from a multitude of locations.       
 
         [0215]    Current methodologies are of two types. One way is for one person to move sequentially to each location of interest, measuring and recording results, and often returning to repeat measurements to note changes. Another method is to deploy multiple operators, each with an expensive handheld instrument, who communicate by shouting, moving for conferences, via walkie-talkies, or via cell phones. The exemplary embodiment of the present invention clearly offers a dramatic improvement in productivity for this type of application through the use of distributed sensor modules that are relatively inexpensive, together with novel formats for measurement presentation that allow quick feedback on control changes and component interactions within HVAC systems. 
       Method for Setting Duct Static Pressure 
       [0216]    In HVAC duct systems it is important to maintain a minimum level of pressure at the extreme end of the duct system in order to maintain airflow through the duct and diffusers. For instance, a building engineer might specify that the fan generate a duct pressure that is 3 inches of water column above the ambient pressure in the building (static pressure), and that the system of valves and dampers be adjusted such that the most remote air diffuser will be supplied air at a pressure of at least 0.5 inches of water column. It is critical that the pressure at this point be carefully controlled. If too low, the diffusers will not distribute conditioned air as designed and building comfort will suffer. If too high, energy is wasted by running the fan too fast. If the technician measures only 0.4 inches of static pressure, he needs to adjust the fan and/or the dampers to increase the remote duct pressure to the minimum of 0.5 specified. However, if the pressure is higher than required, the excess fan power will use far more electricity than it should. The electric power required increases at the cube of the duct pressure increase. For instance, if the fan speed is increased to raise the remote duct pressure to 0.55 inches, only 10% higher than required, the fan will use 30% more electric power than required. (The calculation has the form of 1.1.times.1.1.times.1.1=1.3.) Current procedure requires a technician to measure the pressure at the appropriate point in the duct, and then move through the building to adjust the fan and the dampers. He then returns to measure pressure again. This cycle of measurement and adjustment will be repeated until the specified result is achieved. Sometimes the fan is a long distance from the point being measured, and on a different floor. This repetitive procedure requires a lot of time and effort, and leads to the technician settling for some safe guard-banded pressure instead of achieving the precise result desired. This is one of the main sources of wasted energy in buildings. What the technician needs for applications like this is a stream of real-time measurements taken at the point of interest and delivered to him where and when he is making the adjustment at the point of control. 
       Method 
       [0217]    In accordance with additional embodiments of the invention, a method of achieving a desired set-point for duct static pressure includes the steps of:
       deploy differential pressure sensor modules to the points of interest, which may include not just the end point of a duct, but several points throughout the duct system which may be affected by a control change;   link each sensor module to the control module;   deploy repeater modules if necessary for range;   select a useful display format;   observe existing status of duct system pressures;   effect changes in fan speed or damper settings;   observe static pressure responses to control changes in real time from multiple locations.       
 
       Pipe Fluid Pressures and Temperatures 
       [0225]    System  100  utilizes sensor modules to measure temperature and pressure of fluids in pipes.  FIG. 12  illustrates the use of sensor modules in an exemplary application. Fluid  1200 , e.g., water, moves through pipe  1210 . Pipe  1210  includes three fixtures known as PT test points (pressure and temperature), which are sometimes implemented using a water-tight access port  1213  called a Pete&#39;s Plug. If temperature alone is desired, sensor module  901  from  FIG. 9 , or a similar sensor module, may be inserted through a Pete&#39;s Plug as illustrated at location  1211 . Temperature measurements will be transmitted continuously to control module  110 . 
         [0226]    If pressure is desired as well as temperature, sensor module  1221  may be inserted through a Pete&#39;s Plug as illustrated at location  1214 . Sensor module  1221  allows pressure measurements to be made through a Pete&#39;s Plug. Control module  110  can display multiple pressure and temperature results from multiple locations concurrently. 
         [0227]    Valve  1212  may be adjusted to control the flow of fluid, and a user may desire to know the volumetric fluid flow. Valve  1212  may be calibrated so if the pressure drop across the valve is known, the volumetric flow, e.g., in gallons per minute, can be determined from a chart or equation. Sensor module  1221  can measure the differential pressure between locations  1214  and  1215  as well as the static pressures at each point. All results are transmitted to control module  110 . It is often desirable to have these results available concurrently. It is also often desirable to have these results available from multiple locations concurrently. 
       Method 
       [0228]    In accordance with additional embodiments of the invention, a method of measuring pressure and/or temperatures at a multitude of points in a pipe system concurrently includes the steps of:
       deploy pressure and temperature sensor modules to each point of interest;   if desired, deploy water flow meter with connected instrument interface module;   link each sensor and interface module to the control module;   deploy repeater modules if necessary for range;   select a useful display format;   observe existing status of system pressures and temperatures;   effect changes in pump speed or valve settings;   observe multiple responses to control changes in real time from multiple locations in a user-friendly display format.       
 
       Velocity Sensor Module and Probe Apparatus 
       [0237]    Air velocity is frequently required in HVAC. The present invention includes a velocity sensor module with unique features. A velocity sensor module, in coordination with temperature and/or humidity modules and a control module, form a system of distributed sensors that allows a user to make velocity and pressure measurements in air ducts more rapidly, more conveniently, more accurately, and more safely. The present invention may also be used to measure air velocity and pressure in applications other than ducts. The present invention uses a method based on differential air pressure, which is applicable to traditional velocity probes such as Pitot tubes. 
         [0238]    A widely used formula for air velocity is derived from fundamental laws of physics:
       V=1096.7×square root of (VP/d), where: V is velocity in feet per minute VP is velocity pressure in inches of water column and   d is density of air in pounds per cubic foot=1.325×BP/T, where BP is barometric pressure in inches of mercury and T is absolute temperature=degrees Fahrenheit+460       
 
         [0241]      FIG. 14  illustrates a system  1403  for making measurements of T, BP, and VP of duct air in an air duct. Often these measurements are part of a standard procedure, a velocity traverse of a duct. This procedure determines the conditions at a cross-sectional plane of a duct. Air conditions include barometric pressure, temperature and optionally humidity. Air conditions also include static pressure at one or more points on the cross-section. Conditions also include the inside dimensions of the duct, free of any insulation that may coat the duct walls. From these dimensions, a user consults standard tables and/or formulas to determine the matrix of points in the duct cross-section at which velocity must be measured. Air velocity is not uniform in the cross-sectional plane, so many measurements must be performed at different locations and the results averaged. The average velocity times the cross-sectional area equals the airflow volume at that point in the duct system. 
         [0242]      FIG. 14  illustrates a duct traverse procedure using an exemplary embodiment of the present invention. Air or another gas flows through duct  1401  with duct walls  1402 . Air velocity is not uniform across the duct as illustrated by velocity vectors  1403 . The user must determine an average velocity in the duct by making and storing many measurements at specific locations  1404  located in the cross-sectional plane of the duct  1401 . A user holds Pitot tube  1405  steady at each location  1404 , and makes and stores a velocity reading. Then the user moves the Pitot tube to the next location for another measurement. Industry standard procedures may require measurements at 16 or more, sometimes as many as 200, separate locations in the duct. 
         [0243]    A Pitot tube  1405  has an orifice  1406  at the tip which when facing into the airstream develops total pressure. A Pitot tube has at least one other orifice  1407  that develops static pressure if not directly impacted by the passing airstream. A Pitot tube includes separate channels to conduct the two pressures outside the duct where they may be connected by hoses to velocity sensing module  1410 . One hose connects the static pressure port  1409  of Pitot tube  1405  to the static pressure port  1411  on velocity sensing module  1410 . Another hose connects total pressure port  1408  on Pitot tube  1405  to total pressure port  1412  on velocity sensing module  1410 . 
         [0244]    Velocity sensing module  1410  includes valves, sensors, microprocessors, and other components to accurately measure total pressure, velocity pressure, and static pressure concurrently. The measured values are transmitted to control module  1430 . Sensor module  1420  is inserted through a hole in duct wall  1402  and remains in-situ measuring temperature and/or humidity. The measured values are transmitted to control module  1430 , which calculates and displays all of the results of interest to the user. Control module  1430  may be worn on the user&#39;s wrist, or mounted to the duct wall  1402 , or otherwise placed conveniently. The user may store measurements by reaching to press the keypad of control module  1430 . Alternatively, the user may store results and perform other control functions by pressing buttons on thumbswitch  1431 . Stored results are “stamped” with the associated time and date. The user may choose from a variety of display formats, which are illustrated in  FIG. 15 . The present invention includes means for providing key information of different types to the operator concurrently to save set-up and measurement time and to improve understanding of the environment. Key among those innovative information displays are the concurrent measurements of velocity and static pressure. 
         [0245]      FIG. 16  illustrates some improvements provided over traditional methods. User  1601  holds a traditional velocity meter  1610  in one hand and manipulates the keypad with his thumb. Tubes  1611  and  1612  loop down from Pitot tube  1405 . Tube  1611  has gotten caught on ladder. When the tubes  1611  and  1612  dangle and swing, measurement result may be less accurate. Temperature sensor  1613  is inserted through duct wall  1402  and connected to meter  1610  with a coiled cable. User  1601  stands on a ladder with his head in a dark area above the ceiling tiles. User  1601  moves his head up and down alternately, first up to position Pitot tube  1405  for a measurement at a proper matrix point, then down to view and store the results on the meter.  FIG. 16  illustrates the cumbersome nature of the velocity traverse procedure. It is not uncommon for users to simplify the process by skipping the temperature measurement, which affects accuracy. 
         [0246]    When user  1601  finishes the velocity traverse matrix, he lacks a necessary measurement, static pressure. User  1601  withdraws Pitot tube  1405  and temperature sensor  1613  from the duct. User  1601  removes the temperature sensor. User  1601  disconnects tubes  1611  and  1612  from the meter. User  1601  replaces tube  1611  on the meter at a different port. User  1601  presses keys to change the meter mode from velocity to pressure. User  1601  reinserts Pitot tube  1605  into the duct and orients it into the airstream. User  1601  presses the meter to read and record the static pressure in the duct. 
         [0247]    User  1602  in  FIG. 16  uses system  1403 . Velocity sensor  1410  is attached to Pitot tube  1405  with stiff tubing that does not move during a measurement. The display of control module  1430  and the position of Pitot tube  1405  are both visible to user  1602  without moving his head. No tubes dangle from Pitot tube  1405 . No coiled cable is attached to temperature sensor  1420  to present an obstacle. User  1602  has one arm and hand free to grasp a nearby fixture  1603  for improved safety. Free of cumbersome tubes and cables, and provided more visible results, his motions are faster and more precise. When user  1602  finishes traversing the matrix, he may view all of the measurement results as illustrated by  FIG. 15 . No setup changes are necessary to obtain static pressure. Static pressure was measured concurrently with velocity and temperature. A special interactive display mode of the Control Module facilitates the measurement and provides a convenient display of the results. An element of the present invention is the ability to display related measurements simultaneously when the technician usually requires the knowledge. An example in this case is Duct Static Pressure.  FIG. 15  illustrates an exemplary embodiment of a complete display of desired information. 
       Method of Measuring Duct Static Pressure 
       [0248]    In accordance with additional embodiments of the invention, a method of concurrently measuring temperature, velocity, and static pressure in an air duct includes the steps of:
       deploy insertion temperature sensor module to a suitable duct location;   connect two pressure ports of a velocity sensor module to the static and total pressure ports of a Pitot tube or similar probe;   link control module to temperature sensor and velocity pressure sensor;   place Pitot tube inside an air duct at point of interest;   multiple measurements of multiple types are received from multiple locations and displayed on control module for storage and/or dissemination and/or uploading to computer or Internet.       
 
         [0254]    The various embodiments are used with industry-standard Pitot tubes, which are available for purchase from Dwyer, Cole-Parmer, and other HVAC industrial supply companies. Pitot tubes vary in length from a few inches to five feet or more. 
         [0255]    The Velocity Sensor Module will also support Static Pressure measurement with industry standard static pressure probes. The present invention will support many other forms of velocity and pressure probes. 
       Alternate Embodiments of Velocity Sensor Module 
       [0256]    Sensor module  1410  may be firmly attached to Pitot tube  1405 . Sensor module  1410  may have an enclosure that envelops part of Pitot tube  1405 . Said enclosure may have a part that is shaped like a bicycle handle grip to enhance usability. 
         [0257]    Air density is strongly affected by barometric pressure and temperature. Sensors for those two parameters are therefore necessary parts of an accurate velocity sensing system. The effect of humidity is less pronounced, so humidity sensors are not typically used in velocity measurement systems. The distributed and wireless nature of the present invention makes it easier for the user to utilize a humidity sensor and therefore achieve a higher than normal accuracy. 
       Airflow Sensor Module and Capture Hood Apparatus Airflow Sensor Module 
       [0258]    The various embodiments comprise an airflow sensor module which is used with existing airflow capture hoods.  FIG. 17  illustrates a damper setting procedure performed in two ways. Two rectangular ceiling diffusers  1710  are to have their airflow volume adjusted to meet the specification. Users  1  and  2  use a traditional capture hood and traditional method. User  1  holds a heavy, awkward capture hood tight against the ceiling fixture to try to capture all of the airflow, which flows across velocity grid  1723 . Velocity grid  1723  works on a differential pressure principle similar to that of a Pitot tube. When airstream  1712  flows across velocity grid  1723 , a pressure difference is generated between an upstream pressure in tube  1721  and a downsteam pressure in tube  1722 . These tubes are connected to positive and negative pressure ports on meter  1730 . Meter  1730  measures the differential pressure and calculates a velocity. The meter then multiplies the calculated velocity by the cross-sectional area of capture hood  1720 , and displays a volumetric airflow, e.g., 220 cubic feet per minute (CFM). User  1  sees the result and shouts it to his teammate user  2 . User  2  is on a ladder to reach and adjust the damper that controls flow to ceiling diffuser  1710 . After making an adjustment, user  2  waits for user  1  to shout a changed result. This iterative process repeats until the specified airflow is reached. 
         [0259]    User  3  uses airflow sensor  1740 . Airflow sensor  1740  performs the same measurement and calculation functions as meter  1730 , and transmits continuous results to control module  1742  on the wrist of user  3 . As user  3  adjusts the damper, he sees the changed result in real-time. 
         [0260]    The weight of airflow sensor module  1740  is a small fraction of the weight of meter  1730 , because it is designed for a distributed sensing system, and needs no display, keypad, or other features that burden meter  1730 . It is much easier to lift and place capture hood  1720  with airflow sensor module  1740  installed than for the same capture hood with meter  1730 . This can be done by a human operator, or it can be done by a jack or stand  1750 , which allows one person to perform a damper setting function normally performed by two people. A jack or stand  1750  could also be used with meter  1730 , but user  2  would have to climb down the ladder once in a while to read the displayed result. 
         [0261]      FIG. 17  illustrates another long-standing problem with traditional methods and illustrates a corresponding advantage of a distributed sensing system. As with Pitot tubes, airflow sensors must include air density in the calculation. However, temperature sensor  1731  is typically poorly designed and poorly positioned to contribute an accurate figure. It takes too long, e.g. up to three minutes, for airstream  1712  to heat or cool temperature sensor  1731  to the correct temperature. Most users cannot wait that long so they forego the temperature component and accept an inaccurate result. User  3  has installed a fast-acting temperature sensor on a support strut  1724  of capture hood  1720 . It measurement of temperature is transmitted to control module  1742  and is included in the airflow calculation. Optional temperature features included with control module  1742  are to lock in a particular temperature measurement for use with all subsequent measurements, or to manually enter a known air temperature for use in subsequent airflow calculations. 
         [0262]    Airflow sensor  1740  is far less expensive than meter  1730 , allowing more widespread use. 
         [0263]      FIG. 18  illustrates other unique benefits of the various embodiments. A room has three supply air diffusers  1810  and one return air diffuser  1811 . Jacks or stands  1750  hold four capture hoods in place. As shown in  FIG. 17 , one operator  3  can view the airflow figures for all four diffusers at the same time on one control module  1742 . He can adjust the dampers of one after another without moving the capture hoods. Airflow volumes of diffusers on the same system are often interrelated. Adjusting one damper can cause changes of all four airflows, not just the one an operator is seeking to adjust. With traditional equipment and methods, many iterative measurements are required before each diffuser achieves the specified airflow. In the embodiment, the interrelationships are revealed to the operator and corresponding adjustments can be made quickly, saving a lot of time. The ability to view multiple results concurrently offers an unexpected benefit for operators. 
       Airflow Capture Hood 
       [0264]    A relatively small, lightweight capture hood is utilized for measuring airflow at inlets and outlets. Traditional capture hoods such as capture hood  1720  with meter  1730  in  FIG. 17  weigh about 9 or 10 pounds. Replacing a traditional meter with airflow sensor module  1740  reduces the weight to about 7 pounds. The present invention includes a capture hood  1901  shown in  FIG. 19  that weighs about 3 pounds. Capture hood  1901  is constructed with the same type of aluminum, carbon fiber, and modern fabrics that are used in the construction of tents and clothing for mountain climbing. Capture hood  1901  is not constrained by the need for a mounting platform for a heavy meter. Capture hood  1901  utilizes a frame that is light and relatively flexible compared to traditional capture hoods. Capture hood  1901  comprises two or more optional locations for the airflow sensor  1740 , on the side or beneath the velocity grid. Quick-responding temperature sensor or temperature and humidity sensor  1741  is attached to the upper frame of capture hood  1901  where it will have early contact with the airstream. Capture hood  1901  is affixed to the diffuser such that the operator can move away for adjustments or other measurements. These new methods are not practical for heavy capture hoods, but are practical for a hood weighing only three pounds. In one embodiment, capture hood  1910  comprises a spring hook  1943  that hooks over a vane of diffuser  1710 , and tension holds the light capture hood tightly against the diffuser. In another embodiment, magnets  1944  around the perimeter of capture hood  1901  attract to a ferrous strip around the ceiling diffuser. In a further embodiment, spring clamps may hold capture hood  1901  tightly against the ceiling strips between tiles. Alternatively, a thin, lightweight extensible rod  1945  may be placed between the floor and the capture hood  1901 , pinning it against the ceiling diffuser. 
       Proportional Balancing 
       [0265]    Proportional Balancing of HVAC Duct Systems was discussed above. There is often a need to observe and understand how the adjustment of one diffuser damper is affecting the airflow at the other diffusers in the same duct system. This can be done by propping up a capture hood at a diffuser and wirelessly monitoring it while adjusting other dampers. 
         [0266]    Another way to monitor the change is to use a Pitot tube. It is often easier using magnets and grippers to position a Pitot tube in the duct leading to the diffuser in question than it is to jack up a capture hood against the ceiling diffuser. The Pitot tube can then wirelessly transmit a percentage change in measured velocity at a point in the duct cross-section that represents the total airflow. The important parameter is the percentage change caused by the damper adjustment, not the amount of airflow itself. 
         [0267]    The Velocity Sensor Module of the present invention will make further improvements in the time and accuracy of Proportional Balancing. Using magnets or other holding apparatus, a Pitot tube can be temporarily fixed in place at the center line of the duct feeding the furthest duct, the reference duct, as mentioned above. The air velocity measured at that point can be correlated to the airflow measured through the diffuser. When an adjustment shows that an upstream duct adjustment caused a particular change in the duct velocity, such as 5%, it can be assumed that the airflow also changed by 5%, and an airflow measurement can be avoided. The final airflow can be measured at the diffuser as usual to verify the result, but the intermediate measurements can be avoided and much time saved. 
       Method 
       [0268]    In accordance with additional embodiments, a method of measuring at multitude of locations concurrently includes the steps of:
       deploy sensor modules to the points of interest, including airflow sensor modules on capture hoods, and/or velocity sensor modules on Pitot tubes or similar probes, air pressure sensors attached to duct static pressure sensing probes, and/or room-to-room pressure sensor modules, and/or other related sensor modules;   link each sensor module to the control module;   deploy repeater modules if necessary for range;   select a useful display format;   observe existing status of duct system at a multitude of locations;   effect changes in fan speed or damper settings or other changes;   observe duct system response in real time from multiple locations.       
 
       Other Sensor Modules 
       [0276]    Various embodiments comprise other sensor modules that measure light intensity, radiation, CO2 concentration, CO concentration, motor/fan rotor speed in RPM, degree of incline (for dampers and grille degree of openness), pulse counters (for electric meters and other types), and switches (for doors open/closed and machines on/off). Other sensor modules are constructed in a fashion similar to the temperature sensors of  FIG. 9 . Other sensor modules are illustrated in  FIG. 20A ,  20 B,  20 C. In  FIG. 20A , the sensor module  2001  may have a sensing element as an integral part of the module. Alternatively, a sensor module  2002  may have the sensing element  2020  located in a shaft-type of probe as in  FIG. 20B . Alternatively, as illustrated in  FIG. 20C  a sensor module  2003  may have a sensing element  2030  located at the end of a flexible cable. 
       Instrument Interface Module 
       [0277]    The various embodiments also make existing instruments more useful in several ways. First, the result is sent wirelessly to where it is needed. Second, the control module display and viewing angle will usually be superior. Third, the control module provides a very large memory for storing measurements and provides beneficial statistics that are often missing in other instruments. Fourth, the thumbswitch allows hands-free storage of measurements. Fifth, the measurement data can be shared by multiple technicians in real-time. 
       Digital Outputs 
       [0278]    For instance, this type of Sensor Module can utilize the digital results from existing instruments such as the AirData Multimeter from Shortridge Instruments. This allows the benefits of the present invention to be applied to the use of the third-party meter. Results can be sent wirelessly to a remote location, the user can view the results on his wrist while his hands are free for another operation, a large memory is available for storing data, and the Thumbswitch allows him to store data without moving his arm. The Interface Module is adaptable to match the electrical and mechanical output of the third-party meter. The ADM-870C meter from Shortridge Instruments provides an RS-232C serial data output through a standard round connector. 
       Interface Module for Analog Outputs 
       [0279]    Ultrasonic fluid flowmeters and other existing instruments, sensors, and transmitter have analog outputs such as 0-5 volt, 0-10 volt, and 4-20 mA current loop. This Module uses the same basic foundation as the Digital Interface Module, but includes circuitry to convert the analog measurement to a digital value for wireless transmission. 
         [0280]    Pulse Counters. 
         [0281]    Open/Close Switches. 
         [0282]    Instrument interface modules may have characteristics illustrated in  FIG. 20C . Connector 2030 is designed specifically for the output of the instrument of interest. It is attached to the end of a flexible cable  2031  which carries signals to conversion and wireless circuitry inside module enclosure  2003 . 
       Operation in Exemplary Applications 
       [0283]    The modules (control, sensor, and, if present, thumbswitch, repeater, and other types) are collected and turned on. They automatically join a wireless network and the control module displays a Link Status showing all of the modules in the network. The technician deploys each sensor module as appropriate to the function he is performing, such as temperature, humidity, pressure, etc. The technician straps the control Module to his wrist or otherwise positions it for easy viewing. At specific intervals, the measurements made by the sensor modules are radioed to the control module and displayed. The technician may store the measurements in memory if desired, either by pressing a key on the control module&#39;s keypad or by pressing a key on the thumbswitch. 
         [0284]    The various embodiments address the key deficiencies of other HVAC instruments as noted above. Measurements can be taken at the point of interest and results delivered to the technician for immediate action as necessary. What is delivered is a stream of real-time data, not one or two occasional measurements that represent a particular point in time. The technician&#39;s hands are free to make the physical changes necessary, such as repairs or adjustments. A team of technicians can wear modules and share the results in real-time for improved team productivity. Further, an integrated walkie-talkie is available for team coordination. 
         [0285]    The various embodiments allow the technician to install a remote sensor, then move around the building to make the necessary adjustments while a stream of real-time measurements are radioed to him. Thus informed, the technician can make exactly the right adjustments to achieve a precise result. This saves a lot of time and gives a much better result. 
         [0286]    The various embodiments offer another advantage in that they it can make existing instruments far more useful and productive. This is a uniqueness factor. An example is the AirData Multimeter from Shortridge. These instruments measure air pressure, temperature, velocity, and flow. Model 870C of this series of instruments has a serial output that can feed a stream of data to a wireless module which is a component in the invention. The data is then distributed wirelessly to the wrists of the technician team members, who can quickly make the necessary HVAC adjustments. Following is one example of the power of this improvement. Current practice is for one person to hold up a capture hood to an air outlet in the ceiling while another person climbs a ladder, removes a ceiling tile, and locates the damper that controls the air flow to that diffuser. The meter on the capture hood displays the amount of air coming through the diffuser into the room in cubic feet per minute. The person holding up the heavy capture hood, with some difficulty because of the sight angles involved, then reads the meter&#39;s display and shouts it to his partner, who adjusts the damper accordingly, trying to achieve a specified result. Then the two repeat the procedure until the air flow is within the desired range. Finally, the one holding up the capture hood can lower the instrument and rest. Then the team moves to the next diffuser and repeats the procedure. 
         [0287]    In the various embodiments, the airflow data is collected from the Shortridge meter and wirelessly radioed to the control module where a continuous stream of readings is viewed directly by the technician adjusting the damper. He can adjust the damper smoothly and continuously until the result is precisely at the midpoint of the desired range. The one holding up the hood does not have to read the meter or shout to his teammate; he can concentrate on holding the hood steady. The result of the invention is a faster, more accurate result achieved with less effort and stress on the team. In many cases, the invention allows one person to do the same function, using a jack or prop to hold the hood in place. This type of measurement is performed very frequently, so reducing the manpower required by about 50%, while improving the accuracy of the results, is very important to the HVAC industry. Also, fast, accurate results help reduce the energy used in the building and contribute to the energy goals of the country. 
         [0288]    These system capabilities make possible new, better methods for industrial repairs and adjustments. For instance, they eliminate the back-and-forth nature of many industrial operations where the point of interest is different from the point of control. Instead of a long cycle measurement/adjustment/measurement/etc., a real-time stream of measurements is available at the point where the adjustment is being made, saving time and facilitating a more precise final result. 
         [0289]    The distributed nature of the instrument in the present invention makes it possible for a technician to make the necessary measurements at the location of interest, transmit the measurements quickly to the location where they are most needed for decisions and adjustments, which may be a few feet or hundreds of feet away. The measurement results can be displayed on a wrist-mounted module, a head-mounted module for heads-up viewing, or annunciated in the user&#39;s ear. The user&#39;s hands during this process are free for tasks instead of being occupied by instruments. 
       EXAMPLES 
       [0290]    The TAB Accelerator Kit is composed of a Wrist Reporter, Dongle, and Thumbswitch. There are also accessory cables, batteries, and chargers. The Kit works in conjunction with the Shortridge AirData Multimeters, models 870C and 860C. 
         [0291]    The Wrist Reporter is worn on the wrist of the user or otherwise placed convenient to viewing. Readings from the meter are sent wirelessly to the Wrist Reporter for viewing and storage. This allows the TAB technician to finish projects more quickly with more precise measurements. 
         [0292]    Example: Climb a ladder, move the ceiling tile aside, and prepare to set the damper. Look down at your Wrist Reporter and see the flow readings changing in real time as you move the lever. When the reading matches your target, you mark the lever position and/or tighten the wing nut. You&#39;re done. No more shouting back and forth to your teammate holding the flow hood. The Dongle takes the reading out of the AirData Multimeter and transmits it wirelessly to the Wrist Reporter. Also, it doesn&#39;t matter that the viewing angle to the meter is difficult when the flow hood is overhead. The view that matters is the view of the Wrist Reporter. 
         [0293]    Example: Cut 50% off the time required to perform a duct traverse by freeing your hands of the ADM and by seeing velocity statistics as you proceed. Prepare the duct and Pitot tube or Airfoil as usual. Then place the ADM-870C in the correct measurement mode and set it to AUTO or TREND so it reads continuously. You no longer need to crane your head to see the meter&#39;s display. Hang it on your hip using belt loops. Place the Wrist Reporter on the inside of your Wrist Reporter. Place the thumbswitch on your finger. Now use both hands to position the probe as appropriate. When the position is correct and the measurement on your Wrist Reporter looks valid, press the Thumbswitch button to store the result. As you progress through the matrix of points, the Wrist Reporter automatically shows you the current average velocity, along with the minimum and maximum readings of the traverse. 
       Alternative Embodiments 
       [0294]    The temperature sensing elements used may be 2252-ohm thermistors, 10K-ohm thermistors, thermocouples, or other type of temperature sensor. The enclosure may be plastic or metal. Batteries may vary. 
         [0295]    The General Purpose Sensor Module is configured for use with a variety of sensing probes, both analog and digital, to measure air and water temperatures, humidity, CO, CO2, light intensity, and other parameters. 
       Summary of System-Related Functions and Innovations 
       [0296]    The embodiments of the present invention provide is a system of modules as described above that solve or minimize long-standing industry problems. A wireless network of specialty sensors and a wearable control module allows getting data from the point of measurement to the point of control, and improves communication among team members. 
         [0297]    The present invention offers a large increase in productivity by allowing a technician to move around, climb a ladder, drill a hole, adjust a damper or valve, speed up a pump, or otherwise use his hands and feet to implement changes while knowing the immediate effects of those changes. Multiple team members can each wear a Control Module so they can each receive and view the measurement data directly, which promotes better teamwork and higher productivity. 
         [0298]    These system capabilities make possible new, better methods for industrial repairs and adjustments. For instance, they eliminate the back-and-forth nature of many industrial operations where the point of interest is different from the point of control. Instead of a long cycle measurement/adjustment/measurement/etc., a real-time stream of measurements is available at the point where the adjustment is being made, saving time and facilitating a more precise final result. The distributed nature of the instrument in the present invention makes it possible for a technician to make the necessary measurements at the location of interest, transmit the measurements quickly to the location where they are most needed for decisions and adjustments, which may be a few feet or hundreds of feet away. The measurement results can be displayed on a wrist-mounted module, a head-mounted module for heads-up viewing, or annunciated in the user&#39;s ear. The user&#39;s hands during this process are free for tasks instead of being occupied by instruments. 
         [0299]    The wireless modules provide for many different functions in different applications that previously were not possible or only possible by utilizing multiple instruments. For instance, the present invention includes a mobile, wrist-mountable module that can display two or more measurements simultaneously from different sensors in different locations and store them with the time and date of the readings. These new functions produce huge benefits for several HVAC applications. They give the technician the ability to see all of the related information at the time that he is making a decision about a repair or adjustment. 
         [0300]    The various embodiments combine two operating modes that were previously only available in different instruments. One is a diagnostic or debugging mode used by a technician to discover and promptly fix problems. The other is a monitoring or datalogging mode which collects measurements regularly from distributed sensors over a period of hours, days, or weeks. The data is analyzed later, usually plotted against time to show relationships between events. 
         [0301]    The various embodiments allow a mobile module to display the results in a diagnostic mode from sensors that are also at the same time part of a datalogging network. 
         [0302]    While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention. In addition, modifications may be made without departing from the essential teachings of the invention. It is intended that the invention not be limited by the specific embodiments shown and described. It is intended that the invention be limited only by the claims appended hereto.