Condensate trap and drain for systems under pressure

A condensate removal device for capturing, measuring and removing condensate from a fluid system having air or gas under pressure. The device purges only condensate on demand without loss of relative pressure inherent within the system. A differential pressure sensor senses the low and high level of condensate in a condensate collection reservoir activating a diaphragm type discharge valve venting condensate from the reservoir. Once condensate levels fall below a pre-determined level within the reservoir the valve is closed awaiting accumulation of additional condensate before cycling again.

BACKGROUND OF THE INVENTION 
1. Technical Field 
This device relates to automatic discharge valves used in condensate traps 
associated with fluid pressurized systems. It is required to drain 
accumulated condensate from the traps so that the system will remain free 
of intrained moisture that persist during compression and expansion of 
gases under pressure. 
2. Description of Prior Art 
Prior art devices of this type have been known as float controlled 
condensate traps which increases the possibility of valve sticking which 
allows loss of gas or air under pressure within the system. Prior art 
devices have also utilized timer activated purge valves which can become 
independent from actual condensate levels within the traps again allowing 
for an unwanted loss of pressure. Sensing systems have been developed that 
rely on two condensate sensors with a trap to indicate low and high 
condensate levels within. Single sensor probes have also been illustrated 
that contain two sensing elements in a single probe body allowing for 
reliable selective activation and auditing of the purge valve by separate 
sensing elements within, see for example U.S. Pat. Nos. 1,681,344, 
3,429,329 3,675,673, 4,261,382, 4,308,889, 4,336,821 and 4,914,626. 
In U.S. Pat. No. 1,681,344 a condensate removing system is shown wherein an 
auxiliary condensate discharge pipe and discharge valve utilizes a 
differential of pressure between supply header and discharge header 
requiring an unbalance of air pressure for condensate to be purged from 
the system. 
U.S. Pat. No. 3,429,329 is directed to a drain apparatus for automatically 
draining condensate which determines when condensate collects in the drain 
pipe the differential head pressure between the drain pipe and the chamber 
exert pressure on an air trap. The weight of the diaphragm is thus 
overcome and the air pilot valve closes to shut off flow of compressed air 
to the discharged valve. The pressure in the discharge valve is reduced 
and the fluid is discharged through the drain pipe. 
U.S. Pat. No. 3,675,673 is directed to a pressure activated drain valve 
responsive to differential and fluid viscosity i.e. air and water. 
In U.S. Pat. No. 4,261,382 a condensate drain valve is disclosed wherein 
single and multiple sensors are positioned within fluid transfer system to 
activate an electronic circuit for drain valve operation. Once a probe is 
covered with condensate, a positive output is achieved to an integrated 
circuit that compares same with an inherent value within the circuit 
opening the main valve within a timing event circuit. 
U.S. Pat. No. 4,308,889 is directed to an electric conductive type steam 
trap having a condensate level detecting apparatus connected to a control 
circuit that activates a solenoid valve discharging the condensate. The 
valve activation is timed for closing after a pre-determined time element 
has expired after the condensate detecting probe is free of condensate. 
The probe is a simple on/off signal activation device. 
U.S. Pat. No. 4,336,821 discloses a solenoid activated drain valve in which 
the valve element is a differential piston exposed on opposite faces to 
reservoir pressure normally holding the valve closed and minimizing the 
opening force required to be exerted by the solenoid. A temperature 
responsive heating element protects the valve from freezing while a 
sensing element determines the presence of water allowing the valve to 
operate. 
Finally, in U.S. Pat. No. 4,974,626 a condensate trap valve is shown 
utilizing two sensors positioned in vertically spaced relation to one 
another in a single tube within a condensate accumulation chamber. As the 
first sensor is submerged in condensate a signal is formed indicating low 
level and it is the differential in contact between the two sensors which 
determine an activation of the condensate trap valve within the system. 
OBJECTS AND ADVANTAGES 
Accordingly it is an object of the present invention to provide a 
condensate trap and purging system under pressure which senses the 
appropriate level of condensate within the condensate chamber by the use 
of differential pressure within as sensed by a differential pressure 
sensor which is connected to two input pressure ports within the 
condensate chamber. 
Another objective of the present invention is to provide a modular 
construction of the condensate trap so that the reservoir can be easily 
cleaned and the sensing, electrical and mechanical components can be 
easily maintained, repaired or replaced. 
Other objects and features of the present invention will be obvious to 
those skilled in the art. It should be noted, however, that the drawings 
are designed for the purpose of illustration only and not as a definition 
of the limits of the instant invention, for which reference should be made 
to the claims appended to the hereto. 
SUMMARY OF THE INVENTION 
A condensate removal device that selectively and progressively senses the 
presence and relative amount of condensate accumulating within a 
condensate reservoir. A differential pressure sensing element that 
compares pressure above the condensate to pressure below the condensate 
responds to gradual increases in accumulated condensate and activates a 
control circuit that determines preset condition levels and opens a purge 
valve eliminating condensate from the system. Decrease pressure above the 
condensate defines a purge cycle completion and thus deactivates the purge 
valve. Secondary purge and valve activation is achieved at low condensate 
level if high level is not achieved after a set time to assure the purging 
of sediment build-up without pressure loss within the system.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1-4 of the drawings, a condensate trap and drain valve 
10 can be seen having an upper main cylinder housing 11 and a lower main 
cylinder housing 12. A threaded top cap 13 is positioned between said 
respective housings with a bottom cap 14 threadably secured to the lower 
main cylinder housing 12 defining a condensate reservoir 15 within. The 
upper main cylinder housing 11 has multiple apertures at 17, 18, and 19 
formed within a recessed end portion 20. Said apertures 17 and 18 are 
connector fittings defining a condensate inlet port 17A and a purge outlet 
port 18A respectively. A multiple pin electronic connector fitting 21 is 
threadably secured within said remaining aperture at 19. A secondary 
condensate inlet port 22 is positioned in the top cap 13 and is 
interconnected with said inlet port 17A via an internal passageway 23 best 
seen in FIG. 1 of the drawings. A third condensate inlet port 24 is 
provided within the bottom cap 14 in direct communication with the 
condensate reservoir 15 and said hereinbefore described inlet ports 17A 
and 22. 
The purge outlet port 18A is in communication with a solenoid valve 
assembly 25, best seen in FIGS. 1 and 3 of the drawings. The solenoid 
valve assembly 25 is comprised of a flexible diaphragm 26 which is secured 
around its perimeter between a valve housing 27 and a purge port housing 
28. The diaphragm 26 has a centrally located spring seat fitting 29 and is 
apertured at 30 adjacent said seat fitting which defines a communication 
passageway with a lower purge outlet housing passageway 31 defined by a 
partition 32 within. The lower purge outlet housing passageway 31 extends 
downwardly from the partition 32 to a discharge pipe 33 via an 
interconnecting bore 34 within the top cap 13 between the hereinbefore 
described main cylinder housings 11 and 12. The discharge pipe 33 extends 
from the top cap 13 into the condensate reservoir 15, best seen in FIG. 4 
of the drawings. 
A coil spring 35 extends from the spring seat fitting 29 and abuts against 
the inner portion of the valve housing 28 which defines a fluid passageway 
on one side of the diaphragm 26. The spring 35 urges the diaphragm 26 
against a valve seat 26A formed by a valve port within the housing 27 just 
above the partition 32 as will be well understood by those skilled in the 
art. 
It will thus be evident from the above description that to lift the spring 
seat fitting 29 on the associated diaphragm 26, the force of the spring 35 
must be overcome. In operation, atmospheric pressure is present within the 
purge outlet port 18A above the partition 32 whereas in the condensate 
chamber 15 and the lower purge outlet housing passageway 31 above 
atmospheric pressure is maintained by the system during operation. 
Referring back to FIG. 3 of the drawings, a solenoid 36 can be seen having 
a coil 37 and a plunger 38 which is mounted in the valve housing 27. The 
plunger 38 has a top valve gasket 39 and a bottom valve gasket 40 which 
engages against a valve seat 41 in a pilot orifice passageway 42 that is 
in communication with the purge outlet port 18A. A spring 43 is engaged 
about the plunger 38 urging the bottom valve gasket 40 against the 
hereinbefore disclosed valve seat 41. 
Referring to FIGS. 1 and 4 of the drawings, an electronic differential 
pressure sensor unit 42A shown in broken lines is positioned within the 
upper portion of the housing 11 adjacent the solenoid valve assembly 25 
hereinbefore described. A pressure sensor tube 44 projects vertically 
downwardly from a differential pressure sensor port 44A on the 
differential pressure sensor 42A into the condensate reservoir 15 adjacent 
the bottom cap 14. A second pressure sensing tube 45 projects vertically 
downwardly from a differential pressure sensor port 45A to a point 
adjacent the top of the condensate chamber 15. 
The differential pressure sensor 42A is of a solid state component design 
having a piezoresistive differential pressure sensor (PDPS) 42B that 
converts variation in pressure inputs to a linear variation in a resistor 
network. An amplification section 42C for amplification of the voltage 
variation generated by the variation in resistance from the (PDPS) and 
multiple pressure trip point adjustments 42D that compares voltage levels 
of the amplifier to a user adjustable voltage level by a trip point 
adjustment 62 and generates an output where the levels cross. 
In this application as the condensate C (water) level rises and falls 
within the condensate reservoir 15 the pressure differential changes 
between the top and bottom of the reservoir 15 as sensed by the 
differential pressure sensor 42A interconnected to the respective sensor 
tubes 44 and 45. The corresponding signal from the differential pressure 
sensor 42A is then processed by a control circuit as hereinafter 
described. 
Referring to FIG. 5 of the drawings, a functional block diagram of the 
condensate trap and drain device of the invention is illustrated wherein 
the various components are shown in a control flow diagram path. The 
sensor tube 44 is positioned within the condensate reservoir 15 with a 
condensate level at 56 indicated. The control circuit components are 
illustrated by functional blocks including purge logic block 57, a purge 
timer 58, an overall system timer 59. An alarm logic circuit block 60 
provides an alarm output at 61 which indicates abnormal, no function 
condition within the hereinbefore described system. 
In operation, as the condensate level reaches the pre-determined level in 
the condensate reservoir 15 as set by the trip point adjustment 62, the 
differential pressure changes within the condensate reservoir 15 inducing 
a low, medium and high condensate level as indicated on level indicator 
diodes 63 in the control circuit derived from output signals from the 
pressure sensor 42A. Once a high condensate level is reached a purge state 
is indicated and induced in the system. The solenoid valve assembly 25 is 
activated by a solenoid driver 64 energizing the solenoid coil 37 drawing 
the plunger 38 away from the valve seat 41 allowing condensate in the 
condensate reservoir 15 under the pressure of the system to exit through 
the purge outlet port 18A as illustrated in FIG. 7 of the drawings. As the 
purge of condensate continues and the condensate level drops within the 
condensate reservoir 15, a low level i.e. dropped in pressure differential 
is sensed by input from the sensor tubes 44 and 45 and registered by the 
differential pressure sensor 42A is thus indicated by the level indicator 
light emitting diodes 63 in the control circuit, the purge cycle ends as 
illustrated in FIG. 6 of the drawings and the solenoid valve 25 is closed. 
The condensate level status is thus monitored by the system with the alarm 
logic circuit block 60 and alarm output at 61 being activated within the 
control circuit to indicate lack of valve opening or unusual high or low 
levels of condensate within the condensate reservoir 15. The timer control 
circuits 58 and 59 are provided to oversee and extend purge valve cycles 
if necessary. 
It will be evident from the above description that closed loop condensate 
removal is achieved that purges only on demand avoiding the loss of air 
pressure in a typical air pressurized system 73 on which it is installed 
as illustrated in FIG. 7. 
Referring back to FIG. 5 of the drawings, the functional block diagram of 
the system of the invention, it will be seen that a optional heating coil 
64 is provided within the condensate reservoir 15 having a heater control 
block 65 and a heat indicator at 66. The electrical output from the 
differential pressure sensor 42A is detected and treated by a sensing 
circuit 67 having an oscillator 68, level detection 70 and sensitivity 
adjustment 71 as will be well known and understood by those skilled in the 
art. A power source 72 for the control circuit is provided. 
Thus it will be seen that a new and novel condensate trap and drain for 
systems under pressure has been illustrated and described and it will be 
apparent to those skilled in the art that various changes and 
modifications may be made therein without departing from the spirit of the 
invention, therefore I claim.