11
Troubleshooting
Failure to Open
If the main valve failed to open check the following
possible causes to properly correct the problem.
•
Adjusting spring on pilot may have been
tampered with.
•
Initial pressure may be down due to partially closed
supply valve, clogged strainer or other obstruction.
•
Orifice in No. 5A restriction elbow may be plugged.
No. 4A bleed port fitting may have been omitted
and an open coupling substituted.
• Control pipe may be plugged. Most likely points
of obstruction are at shutoff valve and entrance to
delivery main.
•
Main diaphragm may be broken. Test with air or
water before dismantling.
Failure to Close
If the main valve failed to close check the following
possible causes to properly correct the problem.
•
Adjusting spring on pilot may have been
tampered with.
• Orifice in bleed port No. 4A may be plugged.
• By-pass valve may be leaking.
• On pressure regulators like Type E, the main valve
or pilot may be held open by foreign matter in seat.
To determine which valve leaks, follow these steps.
Close stop valve and 1/4 in. control pipe valve.
1.
Remove bleed port bend so pilot will exhaust
to atmosphere.
2.
Crack inlet stop valve. Steam will issue from
8B tee.
3.
Release compression on adjusting spring to
see if pilot closes tight.
4.
Open and close several times to wash seat.
Steam blowing back from bleed port means
main valve disc is held open by foreign matter.
Steam may wash the obstruction from the seat
if the valve is made to open wide. This can be
accomplished, even at light loads, if the control
point is beyond the outlet stop valve.
5. Reassemble bleed port bend and place
regulator in operation.
6.
Slowly open and close outlet stop valve.
Figure 5
. Dismantling Main Valve
NO. 5A RESTRICTION ELBOW
NEEDLE VALVE OR SCHRADER
NO. 645 AIR VALVE FOR USE WITH
HAND PUMP OR CO
2
CYLINDER
AIR OR WATER
LOADING PRESSURE
PET COCK
PRESSURE GAUGE
FRICTION HERE PREVENTS
STEM TURNING WHILE
REMOVING STEM NUTS
7
Type E
