Cashco DA4 User Manual
INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)
MODEL DA4
(Formerly DA3/4)
DIRECT-ACTING, PRESSURE LOADED
PRESSURE REDUCING REGULATOR
(Model DA3 was identical to DA4 except that the DA3 did not include a lower return spring.)
SECTION I
I. DESCRIPTION AND SCOPE
Model DA4 is a pressure reducing regulator used to control downstream (outlet or P2) pressure. Sizes are
1/2" (DN15), 3/4" (DN20), 1" (DN25), 1-1/4" (DN32), 1-1/2" (DN40), 2" (DN50), 3" (DN80) and 4" (DN100). With
proper trim uti li za tion, the unit is suitable for liquid, gaseous, or steam service. Refer to Technical Bulletin DA4-TB
for design conditions and selection recommendations. (NOTE: This product was formerly identifi ed as a Model
D4; a Model DA4 and D4 are one and the same product.)
This manual does not include instructions related to the various methods of pressure loading a Model DA4
main valve.
SECTION II
IOM-DA4
11-13
II. REFERENCES
Refer to Technical Bulletin DA4-TB for tech ni cal
specifi cations for this reg u la tor.
SECTION III
III. INSTALLATION
CAUTION
For welded installations, all internal trim parts, seals and
diaphragm(s) must be removed from reg u la tor body prior to
welding into pipeline. The heat of fusion welding will dam age non-metallic parts if not re moved. NOTE: This does
not apply to units equipped with extended pipe nip ples.
1. Regulator may be rotated around pipe axis 360
degrees. For ease of maintenance, the rec om mend ed position is with the cover dome (25)
up wards. In liquid service it is recommended
that the cover dome (25) be oriented down wards,
and that a cus tom er supplied and installed vent
valve be pro vid ed at the external sensing connection to bleed-off trapped gas/air under the
diaphragm.
2. Provide space below, above, and around reg u la-
tor for removal of parts during maintenance.
3. Install block valves and pressure gauges to pro-
vide means for adjustment, operation, bypass,
or removal of the regulator. A pipeline strainer
is recommended before inlet to remove typical
pipe line debris from entering valve and damaging
internal “soft goods”, primarily the dynamic seal.
ABBREVIATIONS
CW – Clockwise
CCW – Counter Clockwise
ITA – Inner Trim Assembly
CAUTION
Installation of adequate overpressure pro tec tion is recommended to pro tect the reg u la tor from overpressure and
all down stream equip ment from damage in the event of
regulator failure.
4. Downstream Sensing Installation Considerations
– Internal or External Sensing:
a. The regulator may be installed with internal or
external sensing. Unless otherwise spec i fi ed,
the regulator is supplied by factory with internal
sensing. The regulator may be con vert ed in
the fi eld to external sensing. (See Section VII
Maintenance, Part H – Converting Internal/
External Sensing.
b. Reference DA4-TB, Table DAG-11 for rec om-
men da tions for applying external pressure
sensing.
c. For internal sensing, no external line is re-
quired. For external sensing, use an external
control line. The line is connected from the
1/4" (DN8) NPT tap (Port 5 – See Fig. 6) on
the side of the body di a phragm fl ange to a
pressure tap down stream of the regulator.
Use 1/4" or 3/8" (DN8 or 10) outer di am e ter
tubing or 3/8" (DN10) pipe having an inner
di am e ter equiv a lent to Schedule 40 pipe.
d. For condensable vapors (i.e. steam) slope the
external sensing line downward 2 to 5 de grees
to outlet piping to prevent water pock ets, which
allows the diaphragm chamber to always be
self draining. The external sensing line may
be sloped upward for liquids or gas es.
CAUTION
DO NOT HYDROSTATIC TEST THROUGH AN IN STALLED
UNIT; ISOLATE REGULATOR FROM TEST. The "OUTLET
RATING" as printed on the name plate is the rec om mend ed
“upper op er at ing limit” for the sens ing di a phragm. Higher
pres sures could cause internal dam age. In ad di tion, note
on the nameplate that the Inlet and Outlet pres sure and
temperature ratings are at different levels.
IV. PRINCIPLE OF OPERATION
1. When a loading pressure – P
the top side of a diaphragm, the outlet controlled
pressure – P
– will balance at approximately
2
.90 – .98 of the loading pressure - PL. (NOTE:
Fluc tu a tions in P1 – Inlet Pressure will cause a
deviation in P
– Outlet Pressure due to inverse
2
sym pa thet ic ratio effect.) See Section VIII.
2. Movement occurs as pressure variations register
on the diaphragm. The registering pressure is the
outlet, P
, or downstream pressure. The loading
2
– is applied to
Load
CAUTION
Installation of adequate overpressure pro tec tion is recommended to pro tect the reg u la tor from over pres sure and
all down stream equip ment from dam age in the event of
regulator failure.
Model DA4
SECTION IV
pressure fl uid op pos es di a phragm move ment. As
outlet pres sure drops, the loading pressure push es
the di a phragm down, opening the port; as outlet
pres sure increases, the diaphragm pushes up and
the port opening closes.
3. A diaphragm failure will tend to cause the reg u la tor
to fall below setpoint. A loss of loading pres sure
while inlet pressure is imposed will cause the
regulator to fail close. A com plete diaphragm failure
will cause the inlet process fl uid to mix with the
loading fl uid.
V. STARTUP
1 Start with the block valves closed.
2. Adjust the loading system pressure control de vice
so that main regulator is trying to be con trolled at
0 psig pressure.
3. If it is a “hot” piping system, and equipped with
a bypass valve, slowly open the bypass valve
to preheat the system piping and to allow slow
ex pan sion of the piping. Ensure proper steam
trap operation if installed. Closely monitor outlet
(down stream) pressure via gauge to ensure not
over-pressurizing. NOTE: If no bypass valve is
CAUTION
Do not walk away and leave a bypassed reg u la tor unattended!
2
SECTION V
in stalled, extra caution should be used in starting
up a cold system; i.e. do everything slowly.
4. Crack open the outlet (downstream) block valve
to approximately 10% full open.
5. Slowly open the inlet (upstream) block valve
to about 25% open. Adjust the loading system
pres sure control device setpoint pressure upwards
until the main valve is fl owing. Observe the outlet
pressure gauge to ensure not overpressurizing.
6. Continue to slowly open the inlet (upstream) block
valve until fully open.
7. Continue to slowly open the outlet (downstream)
block valve, especially when the downstream piping system isn’t pressurized. If the outlet (down stream) pressure exceeds the desired pres sure,
close the inlet block valve and go to Step 2. Close
bypass valve approximately 25%, and re peat pro ce dure.
IOM-DA4
8. When fl ow is established steady enough that the
outlet (downstream) block valve is fully open, begin
to slowly close the bypass valve if installed.
9. Develop system fl ow to a level near its expected
normal rate, and reset the regulator set point by
adjusting the loading system pressure control
setpoint to the desired outlet pressure level.
VI. SHUTDOWN
10. Reduce system fl ow to a minimum level and
observe pressure set point. Outlet pressure
will rise from the set point of Step 9 for a Model
DA4. The max i mum rise in outlet pres sure on
de creas ing fl ow should not exceed the 10%. If
it does, consult factory.
SECTION VI
1. Shutoff auxiliary loading pressure source, if sup plied.
2. Shutoff inlet block valve.
3. Allow suffi cient time for the line pressure down-
stream of the inlet block valve to bleed down.
SECTION VII
VII. MAINTENANCE
A. General:
WARNING
SYSTEM UNDER PRESSURE. Prior to per form ing any
maintenance, isolate the reg u la tor from the system and
relieve all pressure. Failure to do so could result in personal injury.
1. The regulator may be serviced without
re mov ing the regulator from pipeline. The
reg u la tor is designed with quick-change trim
to simplify maintenance.
2. Record the nameplate information to req ui si tion repair parts for the regulator. The
in for ma tion should include: size, KM Product
Code, Serial Number, and internal or ex ter nal
sens ing. (NOTE: Never both types of sens-
ing.) If external sensing is used, be sure that
the external sensing line is connected.
3. Refer to Section X for recommended repair
parts. Only use original equipment parts
sup plied by Cashco/KM for re build ing or
re pair ing reg u la tors.
4. Owner should refer to owner's procedures
for removal, handling, cleaning and disposal
of nonreuseable parts, i.e. gaskets, etc.
NOTE: On regulators originally supplied
as “oxygen clean” – Opt-55, maintenance
must include a level of cleanliness equal to
Cashco cleaning standard #S-1134.
4. Shutoff the outlet block valve.
5. Relieve the trapped upstream and downstream
pressure and loading pres sure.
6. The regulator may now be removed from the
pipe line or disassembled for inspection and pre ven ta tive main te nance while in-line.
5. The Inner Trim is re moved and replaced in
the body ( 23) as an assemblage of parts.
The Inner Trim Assembly, here in af ter called
ITA, consists of the following parts:
Item Dynamic
No. Seal Type Part Description
13 ..................... All ..........................Guide Bearing/Piston
14 .....................All ................................. Static Stem Seal
14.1 ............... All ...................... Upper Static Stem Seal
14.2 ............... All ......................Middle Static Stem Seal
14.3 ............... All ...................... Lower Static Stem Seal
15 .....................All ................................ Cage O-ring Seal
16 .................CW,PW .............................................. Wiper
17.1 ..............CW,PW .................................Wiper Washer
17.2 ........... OR,CP,PR ........ Camber Adjusting Washer *
17.3.................. UC.......................................Seal Retainer
19 ..................... All ................................................... Cage
20 ..................... All ...........................................Valve Plug
21 ..................... All ............................................ Seat Ring
27 .....................All ............................. Dynamic Side Seal
27.1 ........... CP,CW ................................. TFE Cap Seal
27.2 ...........CP, CW ..................... O-ring Energizer/Seal
27.3 .............. UC .......... U-Cup Seal w/Metal Energizer
27.4 .............. OR ....................................... O-Ring Seal
27.5 ........... PR,PW ............................. Piston Ring Seal
27.6 ........... PR,PW ............. Piston Ring SST Energizer
* Metal Diaphragm Only.
A detailed view of the dynamic side seal parts
is shown in Figure 1 on the next page.
6. Sub-Sections B. through F. are for con struc tions that do NOT include any Opt-81 High
Outlet Pressures with di a phragm support.
These con struc tions are cov ered in SubSec tion G.
IOM-DA4
3
Type OR — O-Ring
Dynamic Seal
Type PR — PRA
Dynamic Seal
Type CP— TFE Cap
Dynamic Seal
A
Type CW — TFE Cap
Dynamic Seal + Wiper
Type PW — PRA Dy nam ic
Seal + Wiper
Type UC — U-Cup
Dynamic Seal
SECTION "A"
Figure 1: Dynamic Side Seals
4
IOM-DA4
B. Main Valve Disassembly:
12. Remove the ITA by pulling up on the valve
plug (20). Set ITA aside.
WARNING
SYSTEM UNDER PRESSURE. Prior to per form ing any
maintenance, isolate the reg u la tor from the system and
relieve all pressure. Failure to do so could result in personal injury.
1. Shut down system in accordance Section VI.
2. Disconnect the external sensing line, if in stalled.
3. Though it is possible to disassemble the
valve unit while installed in a pipeline, it is
rec om mend ed that maintenance be done in
a shop when possible. The descriptions hereafter will assume shop disassembly. Remove
valve from pipeline.
4. Place the valve unit in a vise with the cover
dome (25) upwards.
5. Loosen the diaphragm fl ange bolts (11) and
nuts (12) uniformly.
6. Place matchmarks on body (23) and cover
dome (25) fl anges. Remove cover dome (25).
7. For composition diaphragm construction, hold
the milled “fl ats” on top of the valve plug (20)
stationary. Loosen and remove the di a phragm
lock nut (7). NOTE: Metal di a phragm con struc-
tions do NOT have a di a phragm lock nut (7).
8. Remove upper diaphragm pressure plate (8).
9. Remove diaphragm(s) (9, 9.1, 9.2, 9.9) and
o-ring upper stem seal (14.1). Examine
diaphragm(s) to determine whether failed;
determine if op er at ing conditions are ex ceed ing pressure, pressure drop or temperature limits.
10. For composition diaphragm construction,
re move lower diaphragm pusher plate (10).
11. Evenly loosen the three cage cap screws (18)
in single revolution increments. Regulator
may con tain a lower piston spring (22); the
ITA should rise as the cage cap screws (18)
are evenly backed out. A down wards holding force should be ap plied to the top of the
piston-guide bearing (13) to pre vent the ITA
from pop ping up as the last threads of the
cage cap screws (18) are backed out.
13. Remove the lower piston spring (22), as ap pli ca ble, from within the body (23).
14. Remove o-ring cage seal (15).
15. If supplied, remove internal sensing drilled
plug (32) using 5/32" (4 mm) Allen wrench.
16. Remove body (23) from vise. Clean all
re us able metal parts according to owner's
pro ce dures.
C. Disassembly of the ITA:
1. Units with Composition Diaphragm(s) (See
Figure 2):
a. Pull the valve plug (20) down wards and
out of the piston-guide bear ing (13) and
out of the cage's (19) bottom, while hold ing the cage (19).
b. Remove the piston-guide bearing (13)
from the upper end of the cage (19).
20
14.2
14.3
13
27
15
16
17
19
21
20
Figure 2: Assembled ITA,
Composition Di a phragm Construction
c. Remove o-ring middle stem seal (14.2)
from piston-guide bearing (13).
d. Examine the com po nents (27.1, 27.2,
27.3, 27.4, 27.5, 27.6) of the dy nam ic
side seal (27) mechanism to de ter mine if
sig nifi cant leakage was oc cur ring. If the
dy nam ic side seal (27) shows signs of
sig nifi cant leakage, de ter mine if op er at-
ing con di tions are ex ceed ing pres sure,
pres sure drop, or tem per a ture limits.
Remove dynamic side seal (27) com po-
nents. Special care should be taken when
using “tools” to remove the components
IOM-DA4
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