VMP-IOMM-2018-2
Fulton Ltd
Page 39
OPERATION - 4
4.2.3.1
SETTING PRESSURE CONTROLS
4.2.3.2
TESTING STEAM PRESSURE CONTROLS
If the pressure control is fitted with a differential scale:
1. Set the main scale pressure to the maximum pressure required (system pressure).
Do not exceed the boiler operating pressure.
2.
Set the differential scale to it’s minimum pressure. If the pressure control has a fixed
differential, i.e. no adjustable differential scale, set the main scale to the maximum pressure
required.
when multiple boilers are fitted with a sequence control:
1. Set the main scale and differential scale as above.
2. Set the setback pressure control to the required set back pressure (see
Appendix D
).
1. Start the boiler.
2. SHUT the main steam valve.
3. Set the Operating Pressure switch to its maximum.
4. Set the High Pressure Limiter to 0.5 barg below the safety valve setting.
5. Allow the steam pressure to rise until the high limit pressure switch trips.
On the steam pressure gauge, check that the pressure is not less than 0.5 barg below the
safety valve lift pressure.
If the pressure is incorrect, repeat steps 2, 4 and 5.
6. OPEN the main steam valve slowly to lower the steam pressure.
7. Reset the operating pressure switch to the required working pressure and the high/low
pressure switch to 0.3 barg - 0.5 barg below the operating pressure switch setting.
8. SHUT the main steam valve.
9. Reset the high pressure limiter and allow the steam pressure to rise until the high/low pressure
switch reduces the burner to low fire, and then the burner shuts down under the Operating
Pressure switch.
10. Readjust if necessary to achieve the required settings.
Note: The requirement for a difference between the operating and high pressure limiter is to prevent unnecessary
high steam pressure faults tripping the burner at no load conditions.
The residual heat in the furnace, the flue pipes and the door refractory is capable of raising steam pressure
slightly, causing the high pressure limiter to trip out.
