RM7898A 7800 SERIES VALVE PROVING PRIMARY RELAY MODULES
13 32-00209—03
Split—The downstream seat (high pressure) test is per-
formed at the Before time and the upstream seat (low
pressure) test is performed during the After time.
The Valve Proving items programmed are:
1. Specify Valve Proving and when to perform it.
2. Specify the time duration of the test (calculated from
Appendix A).
Typical Valve Proving System
Function
Valve Proving consists of monitoring the pressure in the
space between two shutoff valves, MV1 (upstream) and
MV2 (downstream). The Valve Proving function, identified
by letters A through F, operates as follows:
The tolerance on all Valve Proving timing values is ±10%.
The following are steps performed during Valve Proving
tests. This section is for background information and does
not define the exact behavioral requirements.
As the RM7898 starts Purging:
a. MV2 is commanded to be open while MV1
remains closed; to depressurize the space. After
4 seconds, MV2 is commanded closed again.
b. This is followed by a three second delay during
which the Valve Proving pressure switch (VPS) is
ignored.
c. Thereafter, the VPS is monitored for the duration of
the Valve Proving test time and, if it turns on, then a
lockout occurs. (Because the gas pressure has
increased due to a leaky upstream valve.) (Low
pressure test)
d. MV1 is commanded to be open while MV2
remains closed, to pressurize the space. After 4
seconds, MV1 is commanded closed again.
e. This is followed by a three second delay, during
which the Valve Proving pressure switch (VPS) is
ignored.
f. Thereafter, the VPS is monitored for the duration
of the Valve Proving test time and, if it turns off,
then a lockout occurs. (Because the gas pressure
has decreased due to a leaky downstream valve.)
(High pressure test.)
Pressure Switches for Valve Proving
System
The Valve Proving System requires a pressure switch to be
installed to monitor the pressure in the internal space
between the two shutoff valves. Recommended pressure
switches are the following Honeywell non-manual reset
models:
Table 7. Honeywell Pressure Switch Selection for Valve Proving System.
Pressure Switch Selection
1. Determine the maximum operating inlet pressure for
the upstream valve; for example, 5.0 psi (140 in. wc).
2. Divide the inlet pressure by two (2.5 psi [70 in. wc],
for example).
3.
From column 2 in Table 7 find the operating range
upper limit that is closest to but greater than the inlet
pressure divided by two. In the example given, the
possible selections from column 1 are the
C6097A1129 and C6097A1137 with an operating
range upper limit of 7 psi. (The C6097A1079 and
C6097A1087 with an upper limit of 60 in. wc are
close, but 60 in. wc is less than the 70 in. wc mini-
mum, so the next higher range must be selected.)
4. From column 6, select the preferred mounting type,
1/4 in. NPT or Flange. For example, if a flange mount
is required, the pressure switch choice from column
1 would be the C6097A1137.
Pressure Switch Installation and
Adjustment
1. Refer to the instructions for theC6097A Pressure
Switch, form number 65-0237.
2. Install the C6097A Pressure Switch according to the
instructions.
3. Adjust the setpoint to 50% of the maximum operat-
ing inlet pressure for the upstream valve.
4. Complete the operation and checkout procedures in
the instructions.
123456
Model Number
Operating
Pressure Range
Maximum
Differential
(Additive)
Maximum
Continuous Rated
Pressure (psi)
Switch Action at
Setpoint Mounting Type
C6097A1004 0.4 to 5 in. wc 0.24 in. wc 2.9 Breaks N.O. to C
connection on
pressure fall.
1/4 in. NPT
C6097A1053 3 to 21 in. wc 0.48 in. wc 5.0
C6097A1061 Flange
C6097A1079 12 to 60 in. wc 2.4 in. wc 1/4 in. NPT
C6097A1087 Flange
C6097A1129 1.5 to 7 psi 0.3 psi 9.3 1/4 in. NPT
C6097A1137 Flange
C6097A1210 0.4 to 4 in. wc 0.24 in. wc 2.9
To Next Page
Loading...
Need help?
General
