IM-P006-07 CTLS Issue 12
18
5.3 Pressure adjustment springs and ranges
Three colour coded adjustment springs are
available for the following reduced pressure
ranges:
Red 0.2 to 17 bar
Grey
DP143 16.0 to 24 bar
DP163 16.0 to 21 bar
Yellow DP163Y 0.2 to 3 bar
5.4 How to renew or change the control spring
It is not necessary to isolate the valve in order to change the spring.
1. Release the lock-nut (2) and turn the adjustment screw (1) anticlockwise until the spring is slack.
2. Slide out the 'C' washer (3) from underneath the lock-nut and remove the cover (12).
3. Remove the old spring (6) and replace it with a new one remembering to replace the top spring
plate (5).
4. Replace the cover and 'C' washer, and turn the adjustment screw clockwise until the desired pressure
reading is obtained.
5. Holding the adjustment screw in position tighten down the lock-nut making sure the 'C' washer stays in
position.
5.5 How to renew the pilot valve assembly and bellows seal
1. Isolate the reducing valve and zero the pressure.
2. Release the lock-nut (2) and turn the adjustment screw (1) anticlockwise until the spring is slack.
3. Slide out the 'C' washer (3) from underneath the lock-nut and remove the cover (12).
4. Remove the spring (6) and top spring plate (5).
5. Undo the 4 x M10 nuts (8) and remove the spring housing (4), bottom spring plate (7) and the
diaphragms (9).
6. Undo the pipework union nuts and release the 6 mm stainless steel pipework.
7. Undo the nuts (21) and remove the pilot valve housing (10) making sure that the main valve spring (16)
is still positioned correctly on top of the main valve head (17).
8. Unscrew the pilot valve assembly (13) which includes the integral strainer screen (14) by using a 27 mm
A/F socket and also remove the plunger (11).
9. Unscrew the bellows seal assembly (31) using a 24 mm A/F socket. If necessary this bellows seal
assembly can be replaced.
10. With the bellows seal still removed screw in the new pilot valve assembly (13) and tighten down to a
torque of 115 N m.
11. Insert the plunger (11) in from the top and check that there is a gap of 0.7 mm between the top of the
plunger and a straight edge placed across the diaphragm location recess (See Figure 8).
Note: Because of production tolerances the plunger is supplied slightly longer than is always required
and it will generally be necessary to grind or machine material off the top end to give the correct length.
After machining make sure the sharp edges are removed from the top of the plunger as these could
damage the bellows. The 0.7 mm gap (see previous step 11) ensures that with the bellows seal fitted
there is just a slight gap between it and the diaphragm whilst in its neutral position.
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