Flow system control with time delay override means

A vacuum operated sewage system includes a static pressure sensor establishing a trigger signal at a selected first level in a standpipe. The sensor is connected upstream of a discharge control valve and actuates a trigger and timer controller at the selected sensed pressure to establish flow for a predetermined period. A separate air admission control is provided to separately actuate the timer controller if the vacuum level in the sewage flow line drops below a selected level, to thereby reset the system vacuum pressure. The air admission control includes a level trigger valve operable to actuate the controller. A by-pass pressure sensing valve has an input connected to sense line pressure and holds the trigger valve in standby until the line pressure drops below a selected vacuum pressure. A resettable fluid timer is also connected to the level trigger valve and is charged under normal pressure system conditions. The timer holds the trigger valve in the set state for a selected period after the by-pass sensing valve responds to system level pressure decreasing below the selected minimum operating pressure and thereby prevents response to momentary changes in the flow line vacuum level.

BACKGROUND OF THE INVENTION 
This invention relates to a pressure flow controller and particularly to 
such a controller for a vacuum operated flow system having means 
responsive to abnormal conditions to establish a flow. 
In flow systems, the pressure differential for establishing flow may 
include a downstream vacuum source. A temporary storage means such as a 
storage tank, a standpipe or the like within which liquid is stored until 
it reaches a selected level may be incorporated into the system. When such 
a selected level is reached, a discharge apparatus is actuated to remove 
liquid generally until a lower limit is established. 
A particularly satisfactory two-position liquid level controller for a 
vacuum operated sewage disposal system and the like is disclosed in U.S. 
Pat. No. 3,777,778 and in the copending application of Trobaugh et al 
entitled "Flow System With Pressure Level Responsive Air Admission 
Control" filed on Oct. 28, 1977 with Ser. No. 846,405. In that fluid 
system a sensor is mounted upstream of a discharge control valve and is 
connected to actuate a triggered controller having a fluid relay connected 
to charge a fluid timing capacitor which, in turn, actuates a fluid 
switch. 
When the output signal from the sensor is received, the vacuum connection 
to the capacitor is momentarily made and the vacuum established as a 
reference. The storage device signals the fluid switch which actuates a 
pilot valve to open the main valve. The sewage flow continues until such 
time as the main capacitor has totally discharged, at which time the 
switch converts to an "off" condition, resetting the pilot valve and 
moving the main valve to a closed condition. 
In operation of such vacuum operated systems, a low vacuum condition may be 
created in the sewer line between the main control valve and the vacuum 
source by low points in the flow line being filled by sewage and/or by a 
partial system bogdown or water logging. The sewage or water laying in the 
low points thus prevents creation of system vacuum and interferes with 
proper system operation. The system vacuum can be restored by admitting 
air into the system to force the sewage in such low points forward toward 
the collection station and clearing of such low points. 
The above identified application provides an automatic admission control 
means for sensing a low system pressure condition and signalling the 
controller for supplying pressure to the line and thereby positively 
clearing of the system line and re-establishing proper system pressure. 
The particular air admission valve means shown therein includes a diaphragm 
bleed valve connecting the controller trigger input to a signal pressure. 
The bleed valve includes a pressure input connected to the vacuum side of 
the line to establish the trigger signal when the vacuum falls below a 
selected level. A parallel bleed-type reset valve is connected in parallel 
with the trigger valve and is actuated by application of valve opening 
pressure to the main valve to reset the input to the controller. 
Although the air admission control produces a satisfactory means of 
triggering the controller, the inventor has found that undesirable 
triggering may occur under transient pressure conditions. 
Thus, various operating systems may encounter a momentary or transient low 
vacuum pressure condition as a result of normal operation. Under such 
conditions of course, the air admission control unit would normally 
respond to actuate the main valve unit even though the system did not 
require such action. Further, in a vacuum actuated operated sewage flow 
system, a number of valve assemblies may be operating at essentially the 
same static head and as a result of corresponding operations generate a 
momentary low vacuum condition from the main vacuum supply or source. Such 
a condition would, of course, be transmitted to other units and result in 
the further actuation of other valve subassemblies even though, in fact, 
such branches were operating in accordance with designed characteristics 
and there was no need for such additional controlled valve operation. The 
unnecessary operation consumes energy as well as requiring component 
operation without any functional benefit. 
SUMMARY OF THE INVENTION 
The present invention is particularly directed to a sewage system having a 
triggered controller with an automatic pressure level air admission 
control in combination with a timed disable control means which actuates 
an interlock system only with abnormal system pressure conditions existing 
for a sufficient period to warrant establishing of flow. More 
particularly, in accordance with the present invention, an admission 
control means is connected directly to the trigger input of the controller 
or in series with a normal system operating sensor to actuate the 
controller. The air admission control includes an air admission valve 
means, preferably a bleed-type trigger valve, having a pressure input 
connected to the vacuum side of the line to establish the trigger signal 
when the vacuum falls below a selected level. A timing means holds the 
trigger valve insensitive to a momentary change. 
In a particular embodiment, a level sensing valve means is connected to 
sense line pressure and to selectively apply line pressure to a resettable 
timing means and the input of the trigger valve means. The level sensing 
valve means is actuated by application of normal line pressure and 
supplies line pressure to the timing means and the trigger valve means and 
holds the trigger input to the controller in a normal standby state. The 
timing means provides a holding signal to the trigger valve means for a 
selected period after the line signal is removed by actuation of the level 
sensing valve means. The trigger valve means is therefore held in the 
standby state for a selected period after actuation of the level sensing 
valve by the abnormal pressure condition. The period is selected to allow 
transient pressure conditions while maintaining control in response to 
undesirable loss of system vacuum. 
In a preferred embodiment of the invention, the timing means is a 
resettable capacitor or storage means connected in series with a diode and 
the input of the trigger valve means to a pressure sensing line. The 
capacitor is connected to atmosphere through a discharge rate control, and 
is charged under normal line pressure conditions. The level valve means is 
connected to selectively connect the diode to atmosphere and allow the 
capacitor to discharge through the rate control to the trigger level of 
the trigger valve means. The level sensing valve is preferably connected 
via a fluid relay to the line side of the diode. The trigger valve means 
is set to respond to an input vacuum level which is substantially less 
than both system pressure and the pressure operative to actuate the 
sensing valve means, and the trigger valve means is held inoperative by 
the timing capacitor which is normally at line pressure. In this 
embodiment, the trigger valve means provides a connection of the 
controller input to ground or reference pressure in the presence of proper 
system vacuum. If the vacuum should drop below the minimum desired vacuum 
level, the level sensing valve means opens and system pressure is removed 
from the timing means and the trigger valve means. The capacitor then 
begins to charge from the last line vacuum level which will be above the 
level necessary to hold the trigger valve means open. The capacitor thus 
delays the transmission of a switching signal and holds the trigger valve 
open to maintain normal system operation until the capacitor charges to 
the set point of the trigger valve means, at which time the trigger valve 
closes and transmits an air admission control signal to the controller. 
The present invention provides a reliable means which may employ readily 
available components for automatically cycling a controller to introduce 
air into a vacuum operated system permitting normal system operation.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
Referring to the drawing, a sewage flow system, similar to that disclosed 
in U.S. Pat. No. 3,777,778 and particularly the previously identified 
application, includes a vacuum collector 1 at a collection end of a flow 
line 2 coupled to a sewage source 3. A main discharge valve 4 is provided 
in the flow line 2 and is periodically actuated to provide for transfer of 
a predetermined amount of sewage to the collector. A standpipe 5 is 
connected to the upstream end of the flow line 2 and within which the 
sewage will accumulate. As the sewage accumulates, the hydrostatic 
pressure in the flow line 2 increases accordingly. A hydrostatic pressure 
sensor 6 connected to the flow line 2 responds to the hydrostatic pressure 
and at a selected pressure level actuates a pneumatic triggered timing 
controller 7, which, in turn, is connected to actuate a pilot valve 8. The 
main valve 4 is selectively opened and closed by the operation of pilot 
valve 8 connecting pressure to an operating valve chamber 11. The pressure 
responsive valves 4 and 8, sensor 6 and timer 7 are connected directly 
into the vacuum system via a connection tap 9 and a check valve 10 such 
that the system is driven from the line pressure. 
Sensor 6 is a leakport unit having an inlet chamber 12 coupled to the line 
2 to impress flow line pressure upon a diaphragm 13. An adjustable mounted 
orifice unit 14 is located in alignment with the central portion of the 
diaphragm 13 within an exhaust chamber 15 which includes a reference port 
16. The port 16 is connected to atmosphere or reference pressure by an air 
admission control means 18 via a line 19. Control means 18 particularly 
forms an embodiment of this invention, as more fully described 
hereinafter. 
The adjustable orifice 14 of sensor 6 is thus normally connected to the 
exhaust via the port 16, line 19 and air admission control 18 in 
accordance with the spacing of the diaphragm 13 to provide a leakport type 
operation. The output of the sensor 6 is connected to a back pressure 
signal line 21 which is connected to controller 7 which includes a vacuum 
regulator 22 connected to line connection 9 to develop a pressure signal 
to controller 7. A restrictor 23 and time delay unit or capacitor 24 
connects the output of regulator 22 to line 21. 
The output signal from sensor 6, which is either atmosphere or regulated 
vacuum is transmitted via unit 24 to actuate a fluid switching system 25 
which includes a fluid relay 26 coupled through a timing capacitor 27 to 
operate a diaphragm switch 28. The output of switch 28 is connected to the 
input or signal chamber of valve 8 and functions as more fully described 
in U.S. Pat. No. 3,777,778 to operate three-way pilot valve 8 which 
operates main valve 4. 
The air admission control means 18 monitors the vacuum pressure level in 
the line 2 downstream of valve 4, and particularly at connection 9 in the 
illustrated embodiment via a connecting sensing line 29. If the monitored 
vacuum pressure in the flow line 2 drops below a selected vacuum pressure 
level, the control means 18 is actuated to close the connecting line 19 
from port 16, simulate the diaphragm closing of orifice unit 14 and 
trigger the controller 7 to produce a timed opening of the valve 4, 
generally as disclosed in the previously identified copending application. 
Thus, if either the sensor 6 or valve means 18 is actuated, the atmospheric 
pressure to controller 7 is cutoff and controller 7 is triggered to 
initiate a timing cycle which is completed even though the triggering 
source, sensor 6 or air admission means 18, is reset. 
The controller 7 and related valves 4 and 8 are more fully disclosed in the 
above application and are therefore only briefly described herein in 
sufficient detail to clearly set forth the illustrated embodiment of the 
invention. 
The air admission control means 18 includes a trigger valve 30 and a low 
level sensing reset valve 31 connected to control the triggering of 
controller 7 in response to a loss of vacuum at the valve 4, generally as 
in the cross-referenced application. A high level sensing valve 32 and a 
timing means, shown as a fluid capacitor 33, which particularly 
illustrates one embodiment of the present invention, are connected in a 
network 34 to delay the operation of the trigger valve 30 and thereby 
prevent response to momentary transient decreases in the vacuum level in 
line 2. The high level sensing valve 32 is connected to selectively supply 
and by-pass a line pressure connection to the timing capacitor 33, and 
thereby establish a conjoint timed control of the signaling of trigger 
valve 30 in response to loss of vacuum pressure. 
The output side of valves 30 and 31 are connected in parallel between the 
sensor 6 and the atmosphere. Under normal operation, one of the valves 30 
or 31 is open to supply atmospheric pressure to the sensor 6 and provide 
for the normal controller operation. Valve 30 is especially coupled to the 
line 29 via the timing network 34 and reset valve 31 is coupled to the 
output of the pilot valve 8 for sequential controlling of the system in 
response to abnormal pressure conditions, and during normal vacuum 
pressure conditions permitting normal operation of controller 7. 
The illustrated valve 30 is an adjustable set point diaphragm valve similar 
to the pressure regulator valve 22 and the switching valve 28. The valve 
30 thus includes a diaphragm 36 in a valve body 37 and defining a pressure 
input chamber 38 and an output or control chamber 39. The control chamber 
39 includes a port 40 connected to atmosphere at 41 and a nozzle or 
orifice 42 connected by line 43 to the sensor line 19 and reference port 
16. The orifice 42 is opened and closed by the diaphragm 36 which is 
biased to a closed orifice position by a preload coil spring 44 coaxially 
located within the chamber. An adjustment screw 44a is threaded into the 
body and controls the closing force of spring 44 applied to diaphragm 36. 
The pressure input chamber 38 is connected in series with the timing means 
33, as more fully described hereinafter, to the vacuum signal line 
connection or tap 9 to the downstream side of check valve 10 such that the 
vacuum pressure of line 2 is applied to the diaphragm 36. The diaphragm 36 
is, therefore, positioned by the differential fluid pressure in the 
chambers 38 and 39 and the force of spring 44. Under a normal operating 
vacuum level, the pressure differential is such that the spring force is 
overcome, the valve 30 opens and connects the sensor reference port 16 to 
atmospheric pressure. However, as the line vacuum pressure falls, the 
timing network responds to decrease the pressure differential such that at 
a selected pressure level, the spring force predominates and the valve 30 
closes. This cuts off the reference pressure connection, assuming the 
parallel valve 31 is also closed as hereinafter described, and the 
controller 7 is triggered and set to complete a cycle, which functions in 
the same manner as previously described to open the main valve, thereby 
introducing air into the system upstream of the sewage and forcing the 
sewage from the low point. The cycle is completed by the closing of the 
vacuum switch. The initiation of the cycle is controlled by the timing 
network 34 to prevent response to momentary vacuum losses at valve 4. 
The timing capacitor 33 of the air admission control 18 particularly 
provides a time delay in the actuation of valve 30 for preventing system 
triggering as a result of transient changes in the flow line system 
pressure. 
The timing means 33 is any resettable pressure chargeable device, such as a 
fluid storage tank. A discharge orifice 45 is provided to continuously 
discharge the tank at a selected rate to atmosphere. The discharge rate is 
less than the vacuum charging rate with normal vacuum system pressure 
applied via line 29, a restrictor 46 and a diode or check valve 47. Under 
normal operating vacuum pressure, the capacitor tank 33 is therefore held 
at a vacuum pressure essentially corresponding to line vacuum pressure. If 
the line vacuum decreases, the capacitor 33 discharges accordingly. At a 
selected level, generally related to a water logged or sewage block state, 
as previously discussed, the corresponding pressure level actuates valve 
32 which operates to disconnect capacitor 33 from line pressure and 
permits capacitor 33 to discharge to the operating level of trigger valve 
30. The valve 32 and the timing means 33 thus conjointly control the 
trigger valve 30 to automatically trigger the controller 7 to open the 
main valve 4, and, thereby, introduce air into the system, if the vacuum 
falls to a selected level for a selected time period, as follows. 
More particularly, the valve 32 is also a diaphragm operated leakport unit 
corresponding to valves 30 and 31. The input chamber 48 of vacuum level 
sensing valve means 32 is connected to the system sensing pressure line 29 
to the upstream side of the dropping restrictors 46 and 48a. The valve 32 
includes the movable diaphragm 49 defining the input chamber 48 and an 
output chamber 50 which includes a supply port 51 connected to the 
atmosphere and an output orifice 52 connected to an interlock relay 53, 
which is operable to selectively disconnect timing means 33 from line 29. 
A set point adjust spring 54 within the input chamber 48 biases the 
diaphragm 49 to close the orifice 52. A pressure level adjustment screw 55 
controls the setting of the coil spring pressure and with the system 
vacuum pressure applied via the sensing line 29 conjointly establishes 
response to a decrease in system pressure. The interlock relay 53, 
illustrated as a diaphragm unit, includes a diaphragm 56 defining an input 
chamber 57 connected to orifice 52 and dropping restrictor 48a. The output 
orifice 59 is connected to atmosphere. Port 60 is connected between the 
check valve 47 and the dropping restrictor 46 to selectively connect such 
point 61 to ground atmosphere as the reference. In operation, the valve 
means 32 will be set at a selected system pressure such as to hold the 
orifice 52 open as a result of proper system pressure. Atmospheric 
pressure is therefore normally coupled to input chamber 57 of relay 53, 
which is thereby held closed, allowing pressure transmission to the 
capacitor 33 via valve 47. Vacuum pressure is, therefore, applied via 
restrictor 46, check valve 47 and capacitor 33 to the valve 30. The vacuum 
in the input chamber 38 of valve 30 holds it open and establishes the 
response to the sensor 6 as previously described. 
When the line pressure drops to a selected level, valve 32 closes, relay 53 
opens and by-passes the vacuum pressure connection 61 at the input side of 
the check valve 47 directly to atmosphere. The line vacuum is then 
by-passed to atmosphere. The capacitor 33 then discharges toward 
atmospheric pressure via its orifice 45 and after a timing period, the 
capacitor 33 discharges to the trigger level of the valve 30. After such 
time delay, the trigger valve 30 closes, thereby blocking the flow path 
from sensor 6 and developing a back-pressure signal in line 21, in the 
same manner as that previously described. 
As a result of the above, the trigger and timing controller 7 is triggered 
with the same sequence previously described to open the main valve, 
thereby admitting air and perhaps some amount of sewage into the discharge 
system to break any blockage in the system and restore normal system 
operation. 
After initiation and during the forced controller cycle, the air admission 
controller 18 is reset by opening of the reset valve unit 31, as more 
fully described in the cross-referenced application. Generally, reset 
valve 31 is a diaphragm unit having an orifice 62 connected to provide the 
alternate, paralleled connection of the sensor 6 to the atmosphere. The 
input chamber 63 is connected to the input chamber 11 of main valve 4 in 
series with a timing capacitor 64, and a fluid diode 65 shown as a 
diaphragm leakport unit connected to function as a fluid diode. A 
discharge orifice 66 connects capacitor 64 to atmosphere. In the standby 
condition, valve 31 is held closed through the connection to atmospheric 
pressure applied to valve 4 from pilot valve 8. When valve 30 closes to 
trigger controller 7, vacuum pressure is applied through timing capacitor 
64 to the reset valve 31 which now opens and connects the sensor 6 to 
atmosphere. The input to the controller 7 is therefore reset and the 
controller 7 completes the timed cycle. 
Upon completion of the controller cycle, pilot valve 8 resets and main 
valve 4 closes. The valve 30 has been held closed by the opening of main 
valve 4, which results in a drop in the vacuum level at valve 4 as flow is 
created, and thus would tend to trigger a new cycle. However, the reset 
valve 31 is opened, as noted above, and during a short period capacitor 64 
holds valve 31 open by maintaining a vacuum pressure in input chamber 63 
which allows valve 31 to open nozzle 62 and thereby reset the air 
admission controller. 
The system thus resets to the normal standby position in which the system 
is again responsive directly to the operation of sensor 6 or to a 
subsequent drop in line pressure vacuum. 
If system pressure has not been restored, the device again sequences upon 
the closing of reset valve 31, without any further time delay. Thus, the 
low vacuum pressure condition during the cycle is applied and without a 
return of a vacuum state, the means for charging of the time delay 
capacitor 33 of network 34 is lost, and valve 30 remains closed. 
If the operating vacuum pressure has been restored, however, the system 
returns to the standby state with the capacitor 33 charged to hold valve 
30 open. Level pressure sensing valve 32 is also held open by line vacuum 
pressure condition and the ground connection of point 61 removed. 
The time delay network 34 may be set to any desired time period. Generally, 
in a practical system a setting of approximately one minute delay provides 
a highly satisfactory response characteristic. 
Although shown employed as an addition to a hydrostatic sensor controlled 
system, the control means may, of course, be directly applied to actuate 
the illustrated triggered controller or any other similar controller. For 
example, if the connecting line 19 is connected directly to line 21, as 
shown in phantom at 67, and the sensor 6 removed, the system will open 
valve 4 whenever operating line vacuum is lost. 
The illustrated embodiment discloses a preferred and particularly novel 
construction employing a series connected timing means with a selective 
grounding of the input. Various other systems of either a parallel or 
series connection and employing other than the illustrated diaphragm type 
valve means may be employed within the teaching of the present invention. 
The preferred embodiment employs well-known and commercially available 
components and may be attached to existing controllers. The preferred 
embodiment is, therefore, particularly adapted to practical 
implementation. 
Various modes in carrying out the invention are contemplated as being 
within the scope of the following claims, particularly pointing out and 
distinctly claiming the subject matter which is regarded as the invention.