Cashco DA0 User Manual
INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)
MODEL DA0
DIRECT-ACTING, PRESSURE LOADED
PRESSURE REDUCING REGULATOR
for STEAM APPLICATIONS
SECTION I
I. DESCRIPTION AND SCOPE
Model DA0 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). Refer
to Technical Bulletin DA0-TB for design conditions and selection recommendations. (NOTE: This product was
formerly identifi ed as a Model D0; a Model DA0 and D0 are one and the same product.)
This manual does not include instructions related to the various methods of pressure loading a Model DA0
main valve.
SECTION II
II. REFERENCES
Refer to Technical Bulletin DA0-TB and DAG-TB
for tech ni cal specifi cations for this reg u la tor.
CW – Clockwise
CCW – Counter Clockwise
ITA – Inner Trim Assembly
ABBREVIATIONS
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11-13
SECTION III
III. INSTALLATION
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.
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.
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.
4. Steam traps should be installed before and after
the regulator to provide proper drainage.
5. Install the regulator with the fl ow in the direction
of the arrow cast or stamped into the body.
6. For best performance, recommend that the piping upstream and downstream of the regulator
be straignt and free from any restrictions, bend,
etd. which can cause turbulence, for a minimun
length of approximately fi fteen to twenty pipe
diameters.
7. Pipe size should be given special consideration,
particularly downstream of the regulator, to
ensure that the steam velocity does not exceed
industry or customer guidelines. Reference
DAG-TB, Table DAG-11 for rec om men da tions
for applying external pressure sensing.
8. External sensing, uses an external control line.
This line is connected from the 1/4" (DN8) NPT
tap on the side of the pilot body 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. 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.
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.
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.
SECTION IV
IV. PRINCIPLE OF OPERATION
1. The pilot receives steam from the upstream tapping
in the side of the main regulator body and passes
it thru to the cover dome. When a loading pressure – P
– is applied into the top of the cover
Load
dome, the outlet controlled pressure – P
balance at approximately .90 – .98 of the loading
pressure - PL. (NOTE: Fluc tu a tions in P1 – Inlet
Pressure will cause a deviation in P2 – Outlet
Pressure due to inverse sym pa thet ic ratio effect.)
See Section VIII.
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. (For spring loaded pilots, relax the
range spring compression by turning the adjusting
screw CCW.)
– will
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SECTION V
2. Movement occurs as pressure variations register
on the stop plate. The registering pressure is the
outlet, P
, or downstream pressure. The loading
2
pressure fl uid op pos es plug move ment. As outlet
pres sure drops, the loading pressure push es the
stop plate down, opening the port; as outlet pres sure increases, the plug pushes up and the port
opening closes.
3. A loss of loading pres sure while inlet pressure is
imposed will cause the regulator to fail close.
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.
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. Closely monitor outlet
(down stream) pressure via gauge to ensure not
over-pressurizing. NOTE: If no bypass valve is
in stalled, extra caution should be used in starting
up a cold system; i.e. do everything slowly.
CAUTION
Do not walk away and leave a bypassed reg u la tor unattended!
2
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.
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.
IOM-DA0
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
DA0. 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 inlet block valve.
2. Shutoff auxiliary loading pressure source, if sup plied. For spring loaded pilots, relax the range
spring by turning the adjusting screw CCW until
adjusting screw is removed.
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.
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.
Item No. Part Description
7 ...................................................................................Nut
10 ......................................................................Stop Plate
13 ....................................................Guide Bearing/Piston
14 ...............................Lower and Upper Static Stem Seal
15 ..........................................................Cage O-ring Seal
16 ............................................................................ Wiper
17 ...............................................................Wiper Washer
19 ............................................................................. Cage
20 .............................................................................. Plug
21 ......................................................................Seat Ring
27 ....................................................... Dynamic Side Seal
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2. Record the nameplate information to req ui si tion repair parts for the regulator. The
in for ma tion should include: size, Product
Code and Serial Number.
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.
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:
Figure 1: Dynamic Side Seals
3
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.
B. Main Valve Disassembly:
1. Shut down system in accordance Section VI.
2. Disconnect the external piping line(s) connecting pilot to main regulator.
3. Though it is possible to disassemble the main
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 regulator
from pipeline.
4. Place the body in a vise with the cover dome
(25) oriented upwards.
5. Loosen the fl ange bolts (11) and nuts (12)
uniformly and remove.
6. Place matchmarks on body (23) and cover
dome (25) fl anges. Remove cover dome and
gasket (13).
7. Evenly loosen the three cage cap screws
(18) in single revolution increments. NOTE:
Regulator con tains a lower spring (22); the
ITA should rise as the cage cap screws 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
are backed out.
8. Remove the ITA by pulling up on the plug
(20). Set ITA aside.
9. Remove spring (22) from within the body (23).
10. Remove cage o-ring seal (15).
11. 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. To disassemble the ITA, hold the lower part
of the plug (20) in a bench vise; Do not hold
on the machined sur face in the plug's (20)
spindle area. NOTE: The spin dle “slides” in
the "pressed-in-place" lower guide bushing
(24) and the surface can not be marred.
Figure 2: Assembled ITA,
2. Rotate di a phragm lock nut (7) CCW and remove.
3. Remove stop plate (10). Remove ITA from
vise.
4. From below the cage (19) pull the plug (20)
downwards out of the piston-guide bearing
(13) and out thru the bottom of the cage.
5. Remove the piston-guide bearing (13) from
the upper end of cage (19).
6. Examine 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 shows signs
of sig nifi cant leakage, de ter mine if operating
conditions are ex ceed ing pres sure, pres sure
drop, or tem per a ture lim its.
7. Remove top seal (14) and dynamic side seal
(27) and discard. NOTE: Special care should
be taken when using “tools” to remove the
components to ensure that no scratches are
imparted on to any portion of the piston-guide
bearing (13) groove.
8. Remove wiper seal (16)and wiper washer (17)
from within cage (19).
9. Remove lower stem seal (14) from plug (20).
10. Remove seat ring (21) from bottom of cage;
examine for signs of leakage. If seat ring
shows signs of signifi cant leakage, determine
if op er at ing con di tions of pressure, pressure
drop, or temperature are ex ceed ing limits.
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IOM-DA0
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