CLA-VAL
CRD
Pressure Reducing Control
`
CLA-VAL
Europe
www.cla-val.ch
1
-
CRD001SE
A 11/08
`
Installation - Operation - Maintenance
`
DESCRIPTION
The CRD Pressure Reducing Control automatically reduces a
higher inlet pressure to a lower outlet pressure. It is a direct
acting, spring loaded, diaphragm type control that operates
hydraulically or pneumatically. It may be used as a self-
contained valve or as a pilot control for a CLA-VAL main valve.
It will hold a constant downstream pressure within very close
pressure limits.
`
OPERATION
The CRD Pressure Reducing Control is normally held open by
the force of the compression spring above the diaphragm; and
delivery pressure acts on the underside of the diaphragm. Flow
through the valve responds to changes in downstream demand
to maintain a pressure.
`
INSTALLATION
The CRD Pressure Reducing Control may be installed in any
position. There is one inlet port and two outlets, for either
straight or angle installation. The second outlet port can be
used for a gage connection. A flow arrow is marked on the body
casting.
`
ADJUSTMENT PROCEDURE
The CRD Pressure Reducing Control can be adjusted to
provide a delivery pressure range as specified on the
nameplate. Pressure adjustment is made by turning the
adjustment screw to vary the spring pressure on the diaphragm.
The greater the compression on the spring the higher the
pressure setting.
1-
Turn the adjustment screw in (clockwise) to increase
delivery pressure.
2-
Turn the adjustment screw out (counter-clockwise) to
decrease the delivery pressure.
3-
When pressure adjustment is completed tighten jam nut
on adjusting screw and replace protective cap.
4-
When this control is used, as a pilot control on a CLA-VAL
main valve, the adjustment should be made under flowing
conditions. The flow rate is not critical, but generally
should be somewhat lower than normal in order to provide
an inlet pressure several psi higher than the desired
setting.
`
MAINTENANCE
DISASSEMBLY
To disassemble follow the sequence of the item numbers
assigned to parts in the sectional illustration (CRD001TT).
REASSEMBLY
Reassembly is the reverse of disassembly. Caution must be
taken to avoid having the yoke (
17
) drag on the inlet nozzle of
the body (
18
).
The approximate minimum flow rates given in the table are for the
main valve on which the CRD is installed.
Valve Size
1 1/4" -3"
4"-8"
10"-16"
Minimum
Flow l/s
0,95 - 1,9
3,15 - 12,6
19,0 - 41,0
Follow this procedure:
1- Place
yoke
(
17
) in body and screw the disc retainer assembly
(
16
) until it bottoms.
2-
Install gasket (
14
) and spring (
19
) for 2-30 and 2-6.5 psi
range onto plug (
13
) and fasten into body. Disc retainer must
enter guide hole in plug as it is assembled. Screw the plug in
by hand. Use wrench to tighten only.
3-
Place diaphragm (
12
) diaphragm washer (
11
) and Belleville
washer (
20
) on yoke. Screw on hex nut (
10
).
4-
Hold the diaphragm so that the screw holes in the diaphragm
and body align. Tighten diaphragm nut with a wrench. At the
final tightening release the diaphragm and permit it to rotate
5° to 10°. The diaphragm holes should now be properly
aligned with the body holes.
To check for proper alignment proceed as follows:
Rotate diaphragm clockwise and counter clockwise as far as
possible. Diaphragm screw holes should rotate equal distance on
either side of body screw holes ±1/8".
Repeat assembly procedure until diaphragm and yoke are properly
aligned. There must be no contact between yoke and body nozzle
during its normal movement. To simulate this movement hold body
and diaphragm holes aligned. Move yoke to open and closed
positions. There must be no evidence of contact or dragging.
5-
Install spring (
9
) with spring guide (
8
).
6-
Install cover (
5
), adjusting screw (
2
) and nut (
3
), then cap (
1
).
SYMPTOM
PROBABLE CAUSE
REMEDY
No spring
compression
Tighten adjusting
screw
Damaged spring
Disassemble and
replace
Spring guide (
8
) is not
in place
Assemble properly
Fails to
open when
deliver
pressure
lowers
Yoke dragging on
inlet nozzle
Disassemble and
reassemble properly
(refer to Reassembly)
Spring compressed
solid
Back off adjusting
screw
Mechanical
obstruction
Disassemble and
reassemble properly
(refer to Reassembly)
Worn disc
Disassemble remove
and replace disc
retainer assembly
Fails to
close when
delivery
pressure
rises
Yoke dragging on
inlet nozzle
Disassemble and
reassemble properly
(refer to Reassembly)
Damaged diaphragm
Disassemble and
replace
Leakage
from cover
vent hole
Loose diaphragm nut
Remove cover and
tighten nut
Содержание 90-01
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