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INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)
IOM-DA6
MODEL DA6
DA6 - DIRECT-ACTING, PRESSURE LOADED
BACK PRESSURE REGULATOR
SECTION I
I. DESCRIPTION AND SCOPE
The Model DA6 is a pressure loaded back pressure regulator used to control upstream (inlet or P1) 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. Typically installed in a more common “reverse” fl ow direction arrangement that is balanced (to outlet). Refer to Technical Bulletin DA6-TB for design
conditions and selection rec om men da tions. (NOTE: This product was formerly iden ti fi ed as a Model D6; a Model
DA6 and D6 are one and the same product.)
SECTION II
II. REFERENCES
ABBREVIATIONS
11-13
Refer to Technical Bulletin DA6-TB and DAG-TB for
tech ni cal specifi cations of a Model DA6 regulator.
SECTION III
III. INSTALLATION
1. Install per direction of fl ow arrow indicated on body,
or "IN" and "OUT" markings.
2. 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
during initial startup.
3. Provide space below, above, and around reg u la tor
for removal of parts during maintenance.
4. 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 side
seal and V-TFE seat when applied.
5. Upstream Sensing Installation Considerations
– Internal or External Sensing:
a. The regulator may be installed with internal or
external sensing. Unless otherwise spec i fi ed,
CCW – Counter Clockwise
CW – Clockwise
ITA – Inner Trim Assembly
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 DAG-TB, Table DAG-12 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
port 1/4" (DN8) NPT tap (Port 5 – See Fig. 5)
on the side of the body di a phragm fl ange to a
pressure tap upstream of the regulator. Use
1/4" (6.4 mm) or 3/8" (9.5 mm) outer di am e ter
tubing or 3/8" (DN10) pipe having an inner
di am e ter equivalent to schedule 40 pipe.
d. For condensable vapors (i.e. steam) slope the
external sensing line downward 2 to 5 de grees
to inlet piping to prevent water pock ets, which
allows the diaphragm chamber to al ways be
self draining. The external sensing line may
be sloped upward for gas or liquid service; i.e.
non-condensibles.
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.
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CAU TION
DO NOT HYDROSTATIC TEST THROUGH AN IN STALLED UNIT; ISOLATE REGULATOR FROM TEST.
See Technical Bulletin DA6-TB, Table 1; Maximum P
- Inlet Pressure levels for various diaphragm materials by valve body size. Higher pres sures could cause
in ter nal dam age. The name-plate indicates the Inlet
and Outlet pres sure and tem per a ture ratings.
1
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.
SECTION IV
IV. PRINCIPLE OF OPERATION
1. When a loading pressure – P
the top side of a diaphragm, the inlet controlled
pressure – P1 – will balance at approximately
0.96–0.98 of the loading pressure – PL – for the
standard fl ow direction, and at 0.98–1.0 of the load-
ing pressure – PL – for the reverse fl ow direction.
NOTE: Fluctuations in the P2 – Outlet Pressure
will cause a deviation in pressure setpoint – PSP
– the “crack-open” pressure for the stan dard fl ow
direction. This deviation is com pen sat ed away for
the reverse fl ow direction.
2. Movement occurs as pressure variations register
– is applied to
Load
Recommended Piping Schematic
For Back Pressure/Relief Station
CAUTION
In the event of diaphragm failure, the process fl uid
will mix with the loading fl uid.
on the diaphragm. The registering pressure is
the inlet, P1, or upstream pressure. The loading
pressure fl uid op pos es di a phragm movement. As
inlet pres sure in creas es, the diaphragm push es
up, opening the port; as inlet pres sure decreases,
the loading pressure pushes the di a phragm down
and the port open ing closes.
3. A complete diaphragm failure will cause the reg u la tor to fail closed if in the standard fl ow direction
variation, and tend to fail closed in the reverse
fl ow direction but with seat leakage.
4. Loss of loading pressure while inlet pressure is
imposed will cause valve to fail open.
V. STARTUP
1 Start with the block valves closed.
2. Adjust the loading system pressure control device
so that main valve is trying to be controlled at 0
psig pressure.
CAU TION
Do not walk away and leave a bypassed reg u la tor unattended!
SECTION V
3. Crack open manual bypass valve. Initially pres sur ize system while simultaneously controlling
P1 pressure through manual actuation of bypass
valve.
4. 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 inlet
(up 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.
IOM-DA62
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3
5. Open the outlet (downstream) block valve.
8. Fully open inlet block valve.
6. Slowly open the inlet (upstream) block valve to
about 25% open, observing the inlet (upstream)
pres sure gauge. The reg u la tor should be fl ow-
ing. Adjust the loading system pressure control
device setpoint pressure upwards until the main
valve fl ow is shutoff. Observe the inlet pressure
gauge to ensure not over pressurizing.
7. Continue to open inlet block valve until at least
50% open. Set loading system pressure control
device upwards to approximate 80% desired main
valve pressure level.
VI. SHUTDOWN
1. Shutoff auxiliary loading pressure source.
2. Shutoff inlet block valve.
3. Shutoff the outlet block valve.
9. Begin to slowly close the bypass valve if installed.
10. 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 set
point to the desired level.
11. Reduce system fl ow to a minimum level and
observe pressure set point. Inlet pressure will
decrease from the set point of Step 10. The
max i mum build in inlet pressure on increasing
fl ow should not exceed 10%. If it does, consult
factory.
SECTION VI
4. Relieve the trapped upstream and downstream
pressure and loading pressure.
5. 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.
VII. MAINTENANCE
A. General:
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 spare parts for the regulator. The
in for ma tion should include: size, KM Product
Code, and Serial Number.
3. Refer to Section VIII for rec om mend ed spare
parts. Only use original equip ment parts sup plied by Cashco/KM for re build ing or re pair ing
regulators.
4. Owner should refer to owner's pro ce dures for
removal, handling, cleaning and disposal of
nonreusable parts, i.e. gaskets, etc.
NOTE: On regulators originally sup plied as
“oxygen clean” – Opt-55, main te nance must
include a level of clean li ness equal to Cashco
cleaning stan dard #S-1134.
SECTION VII
Item Dynamic Side
No. Seal Type Part Description
7 ......................All ........................Diaphragm Cap Screw
7 ......................All ...........................Diaphragm Lock Nut
8 ......................All .......Upper Diaphragm Pressure Plate
9 ......................All ......................................Diaphragm(s)
10 .....................All ..........Lower Diaphragm Pusher Plate
13 .....................All ....................... Piston/Guide Bearing√
14 .....................All ......................................... Stem Seals
14.1 ............... All ................................ Upper Stem Seal
14.2 ............... All ................................Middle Stem Seal
14.3 ............... All ..............................Lower Stem Seal√
14.4 ............... All ................ Lower Pusher Plate Gasket
20 .....................All ...........................................Valve Plug
27 .....................All ...........................Dynamic Side Seal *
27.1 ...............CP ..................................... TFE Cap Seal
27.2 ...............CP ......................... O-ring Energizer/Seal
27.3 .............. UC .......... U-Cup Seal w/Metal Energizer
27.5 ...............PR ................................. Piston Ring Seal
27.6 ...............PR ................. Piston Ring SST Energizer
28 .....................All ............................................ Seat Disc
29 .....................All ...............................Seat Disc Washer
30 .....................All ......................................Seat Disc Nut
* Possible option is with NO dynamic side seal.
√ 2-1/2" thru 4" body sizes only.
5. The Inner Trim Assembly (ITA) is re moved and
re placed in the body (23) as an as sem blage of
parts. The ITA con sists of the fol low ing parts:
IOM-DA6
A detailed view of the dynamic side seal parts
is shown in Figure 1 on the next page.
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27.2
19
27.6
NOTE: Two
separate piston
rings per
assembly.
19
27.1
20
Type CP— TFE Cap Dynamic Seal
A
27.5
20
19
27.5
27.6
20
Type PR — PRA Dynamic Seal
19
27.3
20
Type UC — U-Cup Dynamic Seal
19
20
Type NO — No Dynamic Seal
Figure 1: Dynamic Side Seals
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B. Main Valve Disassembly:
C. Disassembly of the ITA:
WARNING
SYSTEM UNDER PRESSURE. Prior to per form ing
any maintenance, isolate the reg u la tor from the
system and relieve all pressure. Fail ure to do so
could result in personal injury.
1. Shut down the system in accordance with
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 pipe line, it is rec om mend ed that main te nance be done in a shop
when pos si ble. The descriptions hereafter will
assume shop dis as sem bly. Remove valve
from pipe line.
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 ang es. Completely remove bolt ing
(11,12). Remove the cover dome (25).
7. Grasp opposite edges of diaphragm (9) and
withdraw the ITA from within the cage (19).
Set the ITA aside.
8. Evenly loosen the cage cap screws (18) in
single revolution in cre ments until fully loos ened; remove cage cap screws (18).
1. Body Sizes 1/2" – 2". (See Figures 2 thru 5):
a. Obtain two pieces of square-section
barstock with a 3/8" - 7/16" dimension,
approximately 2 inches long.
b. Place plug into a vise using the bars of
a. above positioned on "fl ats" located on
plug (20) to prevent vise jaw marks from
direct surface contact with the plug (20).
Orient with diaphragms on topside.
c. Sizes 1/2" – 1": Remove diaphragm
locknut (7) by rotating CCW.
Sizes 1-1/4" – 2": Remove diaphragm
cap screw (7) by rotating CCW.
d. Remove upper diaphragm pressure plate
(8).
e. Remove diaphragm(s) (9, 9.1, 9.2, 9.9).
Examine diaphragm(s) to determine
wheth er failed; determine if operating
con di tions are ex ceed ing pressure drop
or temperature limits.
f. For composition diaphragm construction,
remove upper stem seal (14.1).
g. For metal diaphragm construction, re move
lower pusher plate gasket (14.4).
h. Remove lower diaphragm pusher plate
(10).
i. Remove middle stem seal (14.2).
j. Remove plug (20) from vise, rotate end-
for-end, and resecure in vise using same
metal bars of a. above.
k. Loosen seat nut (30) CCW (viewed
from above) ap prox i mate ly two (2) rev o -
lu tions.
l. Remove assembly (20, 27, 28, 29, 30)
from vise. Complete removal of seat disc
nut (30), seat disc washer (29), and seat
disc (28).
9. Pull cage (19) up and out of body.
10. Remove o-ring cage seal (15).
11. Remove lower cage gasket (21).
12. If supplied, remove internal sensing drilled
plug (32) using 5/32" (4 mm) Allen key wrench.
NOTE: Valves with “Large Internal Sensing”
will not be equipped with any plug (32,33).
13. For metal diaphragm constructions, remove
diaphragm gasket (37) from body (23) di a phragm fl ange.
14. Remove body (23) from vise. Solvent clean
all removed metal parts.
IOM-DA6
2. Body Sizes 2-1/2" – 4". (See Figure 6):
a. Place seat disc nut (30) into a vise with
the plug (20) oriented vertically. Do NOT
over-tighten nut (30) in vise.
b. Place closed-end hex wrench onto
di a phragm locknut (7). Place socket
wrench on 3/4" hex upper end of plug
(20). Loos en diaphragm locknut (7) while
holding plug (20) from rotating by socket
wrench. Remove diaphragm locknut (7)
after fully loosened and socket wrench is
removed.
c. Remove upper diaphragm pressure plate
(8).
d. Remove diaphragm(s) (9, 9.1, 9.2, 9.9).
Examine diaphragm(s) to determine
wheth er failed; determine if operating
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Figure 2: Body Sizes
1/2" – 1", Composition Di a phragm
Figure 3: Body Sizes
1/2" – 1", Metal Diaphragm
Figure 4: Body Sizes
1-1/4" – 2", Composition Diaphragm
Figure 5: Body Sizes
1-1/4" – 2", Metal Diaphragm
con di tions are ex ceed ing pressure drop
or temperature limits.
e. Remove up per stem seal (14.1).
f. Remove lower diaphragm push er plate
(10).
g. Remove middle stem seal (14.2).
h. Remove piston/guide bearing (13) with
dynamic side seal (27) in place.
i. Remove lower stem seal (14.3).
j. Place socket wrench on upper end of plug
(20) as in Step b. above. Ro tate plug (20)
CCW (viewed from above) to loosen seat
disc nut (30). Once nut (30) is loos ened,
re move partial as sem bly (20, 27, 28, 29,
30) from vise. Complete re mov al of seat
disc nut (30), seat disc washer (29) and
seat disc (28).
3. Examine the components (27.1, 27.2, 27.3,
27.4, 27.5, 27.6) of the dynamic side seal
(27) to determine if sig nifi cant leak age was
oc cur ring. If the dynamic side seal (27) shows
signs of signifi cant leakage, de ter mine if op-
Figure 6: Body Sizes
2-1/2" – 4", Composition Di a phragm
er at ing conditions are ex ceed ing pres sure,
pres sure drop, or temperature lim its.
Remove dynamic side seal (27) components
from plug (20) for sizes 1/2" – 2", or from piston/guide bearing (13) for sizes 2-1/2" – 4".
Special care should be tak en when using
“tools” to remove the com po nents to ensure
that no scratches are im part ed to any portion
of the plug (20) or piston/guide bearing (13)
groove.
4. Solvent clean all metal parts to be reused.
D. Inspection of Parts:
1. After inspection, remove from the work area
and dis card the old “soft goods” parts (i.e.
o-rings, di a phragms, seals, etc.). Metal di a phragms should be replaced. These parts
MUST be re placed with fac to ry supplied new
parts.
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2. Inspect the metal parts that will be reused. The
parts should be free of surface con tam i nants,
burrs, oxides, and scale. Rework and clean
the parts as necessary. Surface con di tions
that affect the regulator performance are stated
below; replace parts that can not be re worked
or cleaned.
3. QC Finish & Dimensional Requirements:
a. Valve plug (20);
1. No major defects on plug's (20) bot tom guide spindle, or at guide area
near dynamic seal groove.
b. Cage (19);
1. 16 rms fi nish on cylinder bore. No
“ledges” formed due to wear from
moving dynamic side seal (27).
2. 16 rms fi nish on its seating surface
for tight shutoff.
c. Lower guide bushing (24);
1. 16 rms fi nish on bore.
2. Max 0.015 inch (0.38 mm) clearance
be tween valve plug (20) spindle and
lower guide bushing (24).
d. Internal sensing drilled plug (32);
1. Ensure that bore is minimum 0.125
inch (3.20 mm). Drill out as required.
e. Piston/Guide Bearing (13) (2-1/2"-4" only);
1. No defects at guide area near dy nam ic
seal groove.
4. Staging Material for Reassembly.
a. Inspect and clean parts, as necessary,
from the spare parts kit. (See Article VII.
A.4. comments concerning cleaning for
ox y gen service.)
b. Lay out all the regulator parts and check
against the bill of material.
E. Reassembly of the ITA:
1. Position valve plug (20) with seat disc-end
upwards. Place new seat disc (28) into recess of lower end of valve plug (20) properly
ori ent ed.
2. Position seat disc washer (29) next to seat
disc (28).
3. Engage seat disc nut (30) to secure wash er
(29) and seat disc (28) to valve plug (20).
Firmly hand-tighten.
4. Body Sizes 1/2" thru 2":
a. Using the two square-section met al bar-
stock pieces of VII.C.1.a., clamp the plug
(20) into a vise with the plug's (20) spindle
pointed up wards.
b. Using a torque wrench, tighten the seat
disc nut (30) to 20 – 35 ft-lbs. by rotating
CW.
c. Remove assembly (20, 28, 29, 30) from
vise and rotate end-for-end and resecure
in vise using same metal bars.
5. Body Sizes 2-1/2" thru 4":
a. Orient plug (20) with upper end up wards,
place into a vise, grasping the seat disc nut
(30); tighten the vise lightly, only enough
to "hold" the plug (20) from ro tat ing out of
the vise. Caution: Over-tightening the
vise can distort the seat disc nut (30) and
give bad fi nal torque values.
b. Place a torque wrench on the 3/4" hex
upper end of the plug (20); tighten the seat
disc nut (30) to 40 – 60 ft-lbs. by ro tat ing
CW.
6. Installation of dy nam ic side seal (27) (See
Figure 1): (NOTE: Dynamic side seal (27) for
sizes 2-1/2" – 4" is located on the piston/guide
bearing (13). The dynamic side seal can be
installed on a workbench without need of a
vise.)
a. Type CP:
1. Stretch o-ring energizer/seal (27.2)
over low er cir cum fer ence of valve
plug (20), tak ing care not to “cut”
o-ring en er giz er/seal (27.4). Using
thumbs, work the o-ring en er giz er/
seal (27.4) up and into the groove of
the valve plug (20). NOTE: A very
slight amount of fl uid and elas tomer
com pat i ble lu bri cant is rec om mend ed
as an in stal la tion aid. DO NOT “ROLL”
O-RING.
2. Position TFE cap seal (27.1) ring with
rectangular cross-section at lower end
of valve plug (20). Stretch cap seal
(27.1) over low er end of valve plug
(20) us ing thumbs to work the cap
seal (27.1) onto the valve plug (20).
DO NOT USE A TOOL FOR THIS
STEP. Con tin ue pressing cap seal
(27.1) up wards to wards the groove
until the cap seal (27.1) “snaps” into
the groove of the valve plug (20).
b. Type PR:
1. Wrap corrugated metal piston ring
en er giz er (27.6) over lower cir cum fer ence groove of valve plug (20). Us ing thumbs work the energizer (27.6)
into the valve plug (20) groove.
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2. Spread a piston ring seal (27.5) and
slide over lower circumference groove
of valve plug (20), taking care not to
“cut” piston ring seal (27.5). Using
thumbs, work the piston ring seal
(27.5) into the groove of the valve
plug (20). Repeat this pro ce dure
with a second piston ring seal (27.5).
Ori ent/rotate the "splits" in piston ring
seals (27.5) 180° across from each
other.
c. Type UC:
1. Stretch u-cup seal (27.3) over upper
cir cum fer ence of valve plug (20), tak ing care not to “cut” u-cup seal (27.3)
on the protruding shelf that is part of
the valve plug's (20) groove. Ensure
that the u-cup seal (27.3) is oriented
with the center-open-upwards as
shown in Figure 1, as the u-cup seal
(27.3) depends upon the P1-Inlet
Pres sure to pres sure activate the seal
for proper seal ing action.
d. Type NO:
1. For “standard” fl ow direction ap pli ca -
tions, it is not absolutely required that
a dynamic side seal (27) be installed.
(When included with the dynamic seal
(27), better guiding of valve plug (20)
results.) Type “NO” dynamic seal (27)
means NO dynamic seal.
2. The more common “Reverse” fl ow
direction always requires a dynamic
side seal (27).
7. Place fl uid compatible thread anti-seize,
Locktite Corp., "Nickel Anti-Seize", or equal
on thread ed portion of diaphragm cap screw
(7), sizes 1-1/4" and 1-1/2"; or, thread ed post
por tion of valve plug (20), sizes 1/2" – 1" and
2-1/2" – 4". (NOTE: Valves cleaned for oxygen service should use fi sher Scientifi c Co.,
"Fluorolube GR-362", or equal.)
8. Body sizes 2-1/2" thru 4":
a. Place o-ring lower stem seal (14.3) over
upper-end of plug (20) and into groove on
plug (20).
b. Place properly oriented piston/guide bear-
ing (13) over upper-end of plug (20) and
into position on plug (20).
c. Place o-ring middle seal (14.2) over up-
per-end of plug (20) and into groove of
piston/guide bearing (13).
9. Body sizes 1/2 thru 2":
Place new o-ring middle stem seal (14.2) into
groove of valve plug (20) upper surface.
10. Position lower diaphragm pusher plate (10)
on/over upper end of valve plug (20) properly
oriented. For composition di a phragm con struc tion the “tongue and groove” “ridge” should
be on upper side, “fl at” side down wards. For
metal diaphragm construction the “rounded”
surface of the lower diaphragm push er plate
(10) should be on upper side, “fl at” side down-
wards.
11. For composition diaphragm construction, place
new o-ring upper stem seal (14.1) on/over
upper end of valve plug (20) and into groove
of lower diaphragm pusher plate (10).
12. For metal diaphragm construction, place
com pat i ble gasket sealant on both sides and
place new lower pusher plate gasket (14.4)
on/over upper end of valve plug (20) and onto
lower diaphragm pusher plate (10). (Gasket
sealant is Federal Process Corp. "Gasoila",
or equal.)
13. Position new diaphragm(s) (9) on/over upper
end of valve plug (20). NOTE: For multiple
diaphragms (9) that include TFE material, the
TFE should be on the wetted side; for 6-ply
elastomeric TFE diaphragm (9), stackup is
TFE-TFE-HK-HK-TFE-TFE, beginning with
the low er wetted diaphragm (9) fi rst.
14. Position upper diaphragm pressure plate (8)
on/over upper end of valve plug (20) properly oriented. For composition diaphragm
con struc tion the "tongue and groove" "ridge"
should be on lower side, "fl at" side upwards.
For metal diaphragm construction the "round ed" surface of the upper diaphragm pressure
plate (8) should be on lower side, "fl at" side
upwards.
15. a. Body sizes 1/2" thru 1": Engage di a phragm
locknut (7) to thread ed post por tion of
valve plug (20) and torque to 60-70 ft-lbs.
by rotating CW.
b. Body Sizes 1-1/4" and 1-1/2": Insert
anti-seize coated di a phragm cap screw
(7) through stacked parts (8, 9, 10, 14.1,
14.4) and into upper end of valve plug (20).
Torque-tighten diaphragm cap screw (7)
to 120-130 ft-lbs.
c. Body Sizes 2-1/2" thru 4": Engage di a -
phragm locknut (7) to threaded post of
valve plug (20) and wrench-tighten fi rmly.
IOM-DA68
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While re strain ing valve plug (20) from
ro tat ing by torque wrench on upper end
3/4" hex, use another wrench to tighten
diaphragm locknut (7) to a torque of 180200 ft-lbs.
16. This completes assembly of ITA; remove from
vise.
F. Main Reassembly:
1. Place body (23) in a vise.
2. Reinstall internal sensing drilled plug (32) with
compatible thread sealant.
3. Fit the o-ring cage seal (15) into its body (23)
groove.
4. For metal diaphragm construction, place
seal ant (“Gasoila” or equal) on both sides of
diaphragm gasket (37) and position on body
(23) diaphragm fl ange.
5. Position properly oriented lower cage gasket
(21) onto lower shelf of cage (19).
6. Insert cage (19) into body (23) recess. Prop er ly align all cage bolt (18) holes as there is
only one cir cum fer en tial location pos si ble for
this align ment. Engage all of the cage bolts
(18), then evenly screw in the cage bolts in
one-half revolution increments, taking care
NOT TO “COCK” THE CAGE (19) IN THE
BODY. Torque the cage bolts (18) to 13-15
ft-lbs.
7. Dynamic Side Seals:
a. Type CP: Position the ITA's valve plug
(20) lower end over and into upper end
of cage (19) until the cap seal (27.1)
edge touch es the upper lip of the cage
(19). While gently ap ply ing force to press
the valve plug (20) into the cage (19), si mul ta neous ly use hand thumbs to light ly
press the cap seal (27.1) inwards into
the groove of the valve plug (20) until the
cap seal (27.1) “slips into” the cage (19).
DO NOT USE TOOLS, LU BRI CANT, OR
HEAVY FORCE TO ENGAGE THE CAP
SEAL (27.1) INTO THE CAGE (19). Do
not press inwards on the cap seal (27.1)
too much or the cap seal (27.1) may slide
out of its groove.
b. Type PR: Position the ITA's valve plug
(20) lower end over and into upper end
of cage (19) until the lower piston ring
seal (27.5) touches the upper lip of the
cage (19). While gently applying force to
press the valve plug (20) into the cage
(19), simultaneously use fi ngers to lightly
circumferentially press the fi rst (low er)
piston ring seal (27.5) inwards into the
valve plug (20) groove until the fi rst piston
ring seal (27.5) “slips into” the cage (19).
Repeat for the second piston ring seal
(27.5)
c. Type UC: Position the ITA's valve plug (20)
lower end over and into upper end of cage
(19) until the cap seal (27.1) edge touches
the upper lip of the cage (19). While gently
applying force to press the valve plug
(20) into the cage (19), si mul ta neous ly
use hand thumbs to light ly press the ucup seal (27.3) inwards into the groove
of the valve plug (20) until the u-cup seal
(27.3) “slips into” the cage (19). DO NOT
USE TOOLS, LU BRI CANT, OR HEAVY
FORCE TO ENGAGE THE U-CUP SEAL
(27.3) INTO THE CAGE.
d. Type NO: Position the ITA's valve plug
(20) lower end over and into the cage
(19), allowing plug (20) to enter fully.
8. For composition diaphragm construction,
align diaphragm (9) bolt holes with body (23)
di a phragm bolt holes.
9. Aligning matchmarks and bolt holes, place
cover dome (25) onto body (23) diaphragm
(9) fl ange.
10. Reinstall all fl ange bolts (11) and nuts (12)
with nameplate (99) located under one bolt
head. Hand-tighten nuts (12).
NOTE: If a six-ply diaphragm is being used,
it is important that the diaphragm (9) is “pre formed” – pulled together to remove as much
entrapped air as possible and allow formation
of a diaphragm (9) convolution. Starting with
the body bolts and nuts (11,12) hand tight ened,
“preforming” can be accomplished by any one
of the following techniques:
a. Apply 30-50 psig pressure to the valve
inlet and the valve outlet.
OR
b. Block the valve inlet and outlet and apply
30-50 psig under the di a phragm through
the 1/4" NPT (plugged) external pres-
sure sens ing connection on the valve
di a phragm fl ange.
AND
c. Leave pressure on through tightening
of bolt ing (11,12).
IOM-DA6
Page 10
11. Evenly tighten the body bolting (11,12) in an
alternating cross pattern in one revolution
increments to the following torque value:
Body Size Torque
in. (mm) ft-lb (N-m)
1/2"-2" (DN15-50) 30-35 (41-47)
2 1/2"-4" (DN65-100) 45-50 (61-69)
If supplied, remove pressure of previous Step
10.
G. Units with Supported Diaphragm Designs:
1. A supported diaphragm (9) construction is
designated as Opt-81 High Inlet Pressure.
Both upwards and downwards directions
are pro tect ed against pressure reversal; i.e.
pres sure on one side of diaphragm (9) with
no pressure on other side of diaphragm (9).
2. Body Sizes 2" and Smaller; Composition and
Metal Diaphragm. (See Figure 7.)
a. Body (23) is specially machined with a
shelf to capture a lower diaphragm sup port ring (35).
b. Cover dome (25) is specially machined to
provide a surface for the upper di a phragm
(9) support. Lower diaphragm support ring
(35) is captured by its location. Upon removal of cover dome (25) and di a phragm
(9), the lower diaphragm support ring (35)
can be lifted upwards and out of the body
(23) cavity.
c. Reinstallation is a reversal of Step b.
above.
b. Cover dome (25) is specially machined to
provide a surface for the upper di a phragm
(9) support.
c. When disassembling valve unit, after low er
diaphragm pusher plate (10) is removed,
ac cess is provided to extended-length
cage cap screws (18). When screws (18)
are removed, both the cage (19) and the
lower diaphragm support ring (35) are
loose, and can be lifted upwards and out
of the body (23) cavity.
d. Upon reassembly of valve unit, after cage
(19) is positioned in body (23), lower
diaphragm support ring (35) is positioned
with cage (19) fl ange bolt holes (only one
orientation pos si ble) prior to engagement
and tightening of cage cap screws (18).
Torque screws to lev els indicated in SubSection F.7.i., this Section.
H. Converting Internal/External Sensing:
1. Disassemble the regulator and remove the
diaphragm(s) (9) according to Steps 1-12 in
Part B – Main Regulator Disassembly.
2. To convert from internal to external sensing,
remove the drilled pipe plug (32) and install
a solid pipe plug. Reverse this step for con vert ing from external to internal sensing.
3. Reassemble the regulator according to Part
F – Main Regulator Reassembly.
3. Body Sizes 2" and Smaller; Metal Di a phragm.
(See Figure 8.)
a. Body (23) is specially machined with a
shelf to capture a lower diaphragm sup port ring (35) and a groove for lower o-ring
diaphragm seal (65).
b. Cover dome (25) is specially machined to
provide a surface for the upper di a phragm
(9) support and a groove for upper o-ring
diaphragm seal (65). Lower di a phragm
sup port ring (35) is captured by its lo ca tion. Upon removal of cover dome (25)
and di a phragm (9), the lower di a phragm
sup port ring (35) can be lifted upwards
and out of the body (23) cavity.
c. Dual o-ring seals (65) replace the di a -
phragm gasket (37) normally supplied with
standard metal diaphragm con struc tion;
i.e. non-Opt-81.
d. Reinstallation is a reversal of Step b.
above.
4. Body Sizes 2-1/2" and Larger; Composition
Diaphragm. (See Figure 9.)
a. Body (23) is a standard body (23).
I. Pressure Testing:
1. If a hydrostatic pressure test is performed,
pressure must be applied to all three of cover
dome (25), inlet and outlet of body at the same
level.
CAU TION
DO NOT HYDROSTATICALLY TEST WITH OUT
COV ER DOME PRESSURIZED. NOT AD HER ING
WILL DO PHYSICAL INTERNALS DAM AGE THAT
COULD REN DER THE UNIT IN OP ER A BLE.
2. Inboard Leakage Test (Seat + Dynamic Seal
Leakage).
a. Release all loading pressure in cover
dome.
b. Pressurize inlet to 30 psig with air, GN
c. Tube outlet to a beaker of water to ob serve
number of escaping gas bubbles.
Inboard leakage path may be via plug/seat or
dynamic side seal.
.
2
IOM-DA610
Page 11
1
Figure 7: Opt-81 — Composition Diaphragm
Construction, 2" and Smaller
Figure 9: Opt-81 — Composition
Diaphragm, 2-1/2" – 4"
Figure 8: Opt-81 — Metal Diaphragm
Construction, 2" and Smaller
3. Pressure Containment Test.
a. Pressurize inlet, outlet and cover dome
to 150 psig with air or GN2.
b. Soap solution test all external leak points;
plugged connections, diaphragm fl ange
and di a phragm bolting.
4. Excessive leakage will require disassembly,
examination of sealing elements, correction
of problem, reassembly and retesting.
NOTE: This valve is NOT a bubble-tight
shutoff de vice. See DAG-TB, Table DAG-10
for leak age classes.
SECTION VIII
VIII.PRESSURE LOADING
1. Loading pressure can be supplied using various schemes. Please reference DA6/P-LOAD-TB for the schematics
of these various schemes, in clud ing:
• pressure unloading using BPV
• pressure loading using PRV
• pressure loading using I/P transducer
SECTION IX
IX. TROUBLE SHOOTING GUIDE
When trouble shooting this regulator there are many possibilities as to what may be causing problems. Many
times, the regulator itself is not defective, but one or more of the accessories may be. Sometimes the pro cess
may be causing diffi culties.
The key to effi cient trouble shooting is information and communication. The customer should try to be as precise
as possible in their explanation of the problem, as well as their understanding of the ap pli ca tion and operating
con di tions.
IOM-DA6 1
Page 12
It is imperative the following information be provided by the customer:
• Fluid (with fl uid properties)
• Range of fl ow rate
• Range of inlet pressure
• Range of outlet pressure
• Range of fl uid temperature
• Range of ambient temperature
Pressure readings should be taken at every location that pressure plays a role - i.e., regulator inlet (as close as
possible to inlet port), regulator outlet (as close as possible to outlet port), etc.
Following are some of the more common com plaints along with possible causes and remedies.
1. Erratic regulation, instability or hunting.
Possible Causes Remedies
A. Sticking of internal parts A. Remove internals, clean, and if necessary, replace.
B. Load changes are too quick for B. Convert to external sensing (if necessary) and install
system an orifi ce or needle valve in external sensing line.
C. Oversized regulator C. Check actual fl ow conditions; resize regulator for min i mum
and maximum fl ow; if necessary, replace with smaller
regulator.
2. Erratic regulation, instability or hunting (liquid service).
Possible Causes Remedies
A. Air trapped under diaphragm A. Install valve on external sensing port and bleed off air.
(Install regulator upside down to help prevent re oc cur rence.)
3. Upstream pressure too high.
Possible Causes Remedies
A. Supply pressure is down (confi rm A. Increase supply pressure.
on pressure gauge).
B. Undersized regulator. B. Check actual fl ow conditions; resize regulator for min i mum
and maximum fl ow; if necessary, replace with larger
regulator.
C. Pressure loading system pressure C1. Clean restriction or bleed orifi ces.
restricted. C2. Clean fi lter(s).
C3. Clean loading pressure control device.
D. Faulty loading pressure control device. D. Replace/repair loading pressure control device.
IOM-DA612
Page 13
3
4. Diaphragm continually breaks (steam service regulators).
Possible Causes Remedies
A. Stem seals (14) which protect A. Replace with new stem seals (14).
fl uorocarbon elastomer in diaphragm
assembly may have deteriorated.
B. Diaphragm nut (7) may not be B. Confi rm torque value in accordance with Section VII,
torqued to proper value. paragraph E-13.
C. Diaphragm too stiff causing it C. Follow proper preforming and air evacuation techniques
to crack in service. during diaphragm installation in accordance with Section VII,
paragraph F-10.
5. Diaphragm continually breaks (all regulators).
Possible Causes Remedies
A. Differential pressure across dia- A1. Be aware of limits as well as where the various pressures
phragm may have exceeded limits. are acting. Install pressure safety equipment as necessary.
(See Table 1 in Tech Bulletin A2. Consider if full diaphragm support, Opt-81, should be added.
DA6-TB.)
6. Leakage at diaphragm fl ange.
Possible Causes Remedies
A. Body bolts not torqued properly. A. Torque to proper value (see Section VII, paragraph F-11).
B. Pressures at diaphragm may be B. Consult factory.
too high for regulator design.
7. Leakage across seat.
Possible Causes Remedies
A. Contamination (debris) in regulator. A. Remove internals, clean, and if necessary, replace
sealing and seating elements. *
B. Oversized regulator; valve plug B. Check actual fl ow conditions; resize regulator for minimum
operates directly next to seat. and maximum fl ow; if necessary, replace with smaller
regulator.
* Excess seat leakage may be diagnosed when a failure of the dynamic side seal has occurred. Inspect both
potential internal leak paths.
IOM-DA6 1
Page 14
SECTION X
X. ORDERING INFORMATION
NEW REPLACEMENT UNIT vs PARTS "KIT" FOR FIELD REPAIR
To obtain a quotation or place an order, please retrieve the Serial Number and Product Code that was stamped on
the metal name plate and attached to the unit. This information can also be found on the Bill of Material ("BOM"),
a parts list that was provided when unit was originally shipped. (Serial Number typically 6 digits). Product Code
typical format as follows: (last digit is alpha character that refl ects revision level for the product).
–
NEW REPLACEMENT UNIT:
Contact your local Cashco, Inc., Sales Rep re sen ta tive with the Serial Number and Product code.
With this information they can provide a quotation
for a new unit including a complete description,
price and availability.
CAUTION
Do not attempt to alter the original construction of
any unit without assistance and approval from the
factory. All purposed changes will require a new
name plate with appropriate ratings and new product code to accomodate the recommended part(s)
changes.
–
7
PARTS "KIT" for FIELD REPAIR:
Contact your local Cashco, Inc., Sales Rep re sen ta tive with the Serial Number and Product code.
Identify the parts and the quantity required to repair
the unit from the "BOM" sheet that was provided
when unit was originally shipped.
NOTE: Those part numbers that have a quantity indicated
under "Spare Parts" in column "A” refl ect minimum
parts required for inspection and rebuild, - "Soft
Goods Kit". Those in column “B” include minimum
trim replacement parts needed plus those "Soft
Goods" parts from column "A".
If the "BOM" is not available, refer to the crosssectional drawings included in this manual for part
identifi cation and selection.
A Local Sales Representative will provide quotation
for appropriate Kit Number, Price and Availability.
IOM-DA614
Page 15
5
Model DA6
Composition Diaphragm
FTO – Reverse Flow Direction
Item No. Description
7 Diaphragm Cap Screw or Diaphragm Lock Nut
8 Upper Diaphragm Pressure Plate
9 Diaphragm
9.1 Diaphragm (Material #1)
9.2 Diaphragm (Material #2)
9.9 Diaphragm TFE Cover
10 Lower Diaphragm Pusher Plate
11 Flange Bolts
12 * Flange Bolting Nuts
14 Stem Seal
14.1 Upper Stem Seal
14.2 Middle Stem Seal
15 Cage Seal
18 Cage Cap Screws
19 Cage
20 Valve Plug
21 Lower Cage Gasket
Item No. Description
23 Body
24 Lower Guide Bushing
25 Cover Dome
26 Tap Plug (Not Shown)
27 Dynamic Side Seal
27.1 TFE Cap Seal
27.2 O-ring Energizer/Seal
27.3 U-cup with Metal Energizer
27.5 Piston Ring Seal
27.6 Piston Ring Energizer
28 Seat Disc
29 Seat Disc Washer
30 Seat Disc Nut
32 Internal Sensing Plug (External Sensing Only)
33 Internal Sensing Drilled Plug (Internal
Sensing Only)
99 Nameplate
–ˇˇ
* Not required on 2" CS & SST Body Material.
See Figures 2 – 6 for alternate plug constructions.
For sizes 2-1/2" thru 4", see diaphragm/plug construction in Figure 6.
The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to be
construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. We reserve the right
to modify or improve the designs or specifi cations of such product at any time without notice.
Cashco, Inc. does not assume responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use and maintenance of any
Cashco, Inc. product remains solely with the purchaser.
IOM-DA6 1
Page 16
Model DA6
Metal Diaphragm
FTC – Standard Flow Direction
Item No. Description
7 Diaphragm Lock Nut
8 Upper Diaphragm Pressure Plate
9 Diaphragm
9.1 Diaphragm (Material #1)
9.2 Diaphragm (Material #2)
9.9 Diaphragm TFE Cover
10 Lower Diaphragm Pusher Plate
11 Flange Bolts
12 * Flange Bolting Nuts
14 Stem Seal
14.2 Middle Stem Seal
14.4 Lower Pusher Plate Gasket
15 Cage Seal
18 Cage Cap Screws
19 Cage
20 Valve Plug
21 Seat Ring
23 Body
Cashco, Inc.
P.O. Box 6
Ellsworth, KS 67439-0006
PH (785) 472-4461
Fax. # (785) 472-3539
www.cashco.com
email: sales@cashco.com
Printed in U.S.A. DA6-IOM
Cashco GmbH
Handwerkerstrasse 15
15366 Hoppegarten, Germany
PH +49 3342 4243135
Fax. No. +49 3342 4243136
www.cashco.com
Email: germany@cashco.com
Item No. Description
24 Lower Guide Bushing
25 Cover Dome
26 Tap Plug
27 Dynamic Side Seal
27.1 TFE Cap Seal
27.2 O-ring Energizer/Seal
27.3 U-cup with Metal Energizer
27.4 O-ring Seal
27.5 Piston Ring Seal
27.6 Piston Ring Energizer
28 Seat Disc
29 Seat Disc Washer
30 Seat Disc Nut
32 Internal Sensing Plug (External Sensing Only)
33 Internal Sensing Drilled Plug (Internal
Sensing Only)
37 Diaphragm Gasket
99 Name Plate
Cashco do Brasil, Ltda.
Al.Venus, 340
Indaiatuba - Sao Paulo, Brazil
PH +55 11 99677 7177
Fax. No.
www.cashco.com
Email: brazil@cashco.com
* Not required on 2" CS & SST Body Material.
See Figures 2 – 6 for alternate plug constructions.
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