Interesting John.......how did you over pressurise your gauge?
When attempting a static boiler test combined with setting the gas regulator pressure, I filled the syphon tube with water to the level of the union, however the pocket of air between the syphon union and the burden tube caused the decay
One extra squeeze on the hand pump [7x6] sent the pressure from 6 Bar to overscale = one dead gauge 
So in essence, I need to lock 4.5 Bar cold water pressure with ZERO decay to satisfy the inspector, then for my own benefit set the gas regulator from an unrestricted gas flow to metre down to pilot light 'pressure' at just below 3 Bar working steam pressure
All good fun......... Derek
Hi Derek,
Boiler type = ACSVB-2.
Serial number = 74682.
Working pressure = 45psi.
Initial Hydraulic test pressure (2x wkg.) = 90psi.
Retest Hydraulic Pressure (1.5x wkg.) = 67.5psi.
1. What was your inspector doing testing your boiler to 6 Bar?... that is 2 x working pressure and should not need doing... especially with an attached small pressure gauge with a max capacity of 80psi.
A 2x wkg. pressure test should always be carried out with NO fittings in place.
2. The only test your boiler should need is one at 1.5x wkg. pressure, i.e. 67.5psi... which can be performed with the pressure gauge and other fittings attached, however, the inspector should be sure he can EASILY creep up to this pressure without ANY risk of over pressure... It would seem he did not do this and, in my book, he owes you a new pressure gauge... since, clearly, his test equipment was not up to scratch.
3. There will always be a small amount of air trapped in the bourdon tube with these small gauges and it would NOT be the cause of DECAY... that would be the result of leakage somewhere... possibly through the valves on the hand pump used for testing or elsewhere.
The only time such a small amount of trapped air would cause issues would be if the temperature (ambient) changed drastically... in which case thermal exchange via the walls of the boiler would have more effect.
This is the main reason the test water should be at Ambient Temperature to start with and the test environment should also be reasonably well Temperature Stable (at least for the duration of the test).
4. I would not recommend using a 10Bar (145psi) gauge on your boiler... these small gauges are not very accurate at either end of their scales... typically you would use a gauge of 2x working pressure such that the red line point falls approx MID-RANGE, which is where these small gauges are most accurate... hence the 80psi gauge supplied with your boiler.
Red lining would usually be done with the gauge attached to a SUITABLE test rig fitted with a calibrated and certified test gauge.
This would then be the red line pressure level used during the steam accumulation test.
The inspector could also test the pressure gauge at 1.5 times wkg. pressure using this test rig (and YES there will be some trapped air in the bourdon tube) so this would rule out the DECAY being caused by the trapped air.
If your boiler tester is trying to convince you otherwise then he should not be doing the job.
OK enough said.
How are things with you and the family? are you ready for the Christmas feasting a drinking? (not necessarily in that order).
Best regards, Happy Christmas and a peaceful New Year to you and yours.
Your old Friend.
Sandy.
