VALVE LEAK TEST (Fig. 7)
This is a test for checking the closure tightness of a gas
safety shutoff valve. It should be performed by qualified
personnel during the initial startup of a burner system, or
whenever the valve or valve bonnet is replaced (see Service
Information section). It is recommended that this test also
be included in the scheduled inspection and maintenance
procedures. For a periodic inspection test, follow steps 1,
3, 4, 5, 8, 9, 10, 12, 13, 16, and 17.
1. De-energize the control system to assure that there is
no power to the safety shutoff valve (C) shown in Fig. 7.
2. Close the upstream manual gas cock (A).
3. Make sure the manual test petcock (F) is closed in the
leak test tap assembly (D).
4. Remove the leak test tap plug and connect the test
apparatus to the Leak Tap (D).
5. Close the downstream manual gas cock (E).
6. Open the upstream manual gas cock (A).
7. Run the safety shutoff valve (C) to its fully open
position (through the safety system); then immediately de-
energize the system to close the valve.
8. Immerse a 1/4 in. tube vertically 1/2 in. (12.7 mm) into
a jar of water.
9. Slowly open the test petcock (F).
10. When the rate of bubbles coming through the water
stabilizes, count the number of bubbles appearing during a
ten-second period. Each bubble appearing during a ten-
second period represents a flow rate of approximately
To meet U.S. requirements, leakage must not exceed the
3/4, 1, 1-1/4, 1-1/2
2, 2-1/2, 3
a Based on air at standard conditions, test pressures pro-
vided by ANSI Z21.21, Section 2.4.2 and a maximum of
235 cc/hr per inch of seal-off diameter. Seal-off diameter
is not to be confused with pipe size.
1. Before servicing, turn off the gas supply and dis-
connect all electrical power to the valve actuator.
2. Only qualified service technicians should at-
tempt to service or repair flame safeguard con-
trols and burner systems.
3. Do not disassemble the valve bonnet assembly;
the valve seat is not replaceable.
4. Failure to properly position and seat the seals in
the valve body may result in a hazardous gas
OPERATION AND CHECKOUT • SERVICE INFORMATION
NOTE: For international leak test requirements, contact the
office of the appropriate approval agency.
AFTER THE TEST:
11. Close the upstream manual gas cock (A).
12. Close the test petcock (F), remove the test apparatus,
and replace the leak test tap plug (D).
13. Open the upstream manual gas cock (A) and energize
the safety shutoff valve (C).
14. Test with soap bubbles to assure that there is no leak at
the test tap (D).
15. De-energize the safety shutoff valve (C).
16. Open the downstream manual gas cock (E).
17. Restore the system to normal operation. If two safety
shutoff valves are utilized, each 550V valve is to be checked
for tightness of closure.
Fig. 7—Valve Leak Test.
1/4 in. FLEXIBLE
1/4 in. ALUMINUM
OR COPPER PILOT
MAY ALSO BE A PERMANENT PETCOCK.
SCHEDULED INSPECTION AND MAINTENANCE
Setup and follow a schedule for periodic inspection and
maintenance, including the burner, all other controls, and
the valve(s). It is recommended that the Valve Leak Test in
the Checkout section be included in this schedule. Refer to
the Instructions for the primary safety control for more
VALVE BONNET REPLACEMENT
The entire valve bonnet may be replaced without re-
moving the valve body from the gas line. Do not disas-
semble the valve bonnet assembly; the valve seat is not
JAR OR GLASS