Maxon's web site is
The site offers installation guide downloads for all its shut-off valves.
Each guide includes a procedure for a periodic test.
One such test (of two in the guide), for the 4700 valve is below.
You should find the test for your specific valve.
Suggested leak test procedure for
double-blocking shut-off valves
(without vent line)
(a) Shut down combustion system per manufacturer’s
recommended procedure.
(b) Close manual valves A and B.
(c) Visually inspect to verify that shut-off valves #1
and #2 are closed.
(d) Remove the 1/4” pipe plug from downstream side
of shut-off valve #1. Install leak test apparatus.
Safely vent any trapped gas pressure.
(e) Open manual shut-off valve A, then close leak
test apparatus. Insert tube into a container of
water just below the surface.
(f) Open test apparatus and test valve for leakage.
As a guideline, valve should be tested for 2
minutes per inch of pipe diameter. Large diameter
pipes or long piping runs between shut-off valves
may need additional testing time.
(g) If valve testing indicates leakage exceeding 15
bubbles per minute, perform pre-operational
exercising as outlined on Page 6100-S-2 and
retest the valve. If valve continues to exceed
allowable leakage limit, remove from service and
contact Maxon.