Page 1
INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)
IOM-DA8/9
MODEL DA8 & DA9
DA8 - DIRECT-ACTING, POSITIVE BIAS DIFFERENTIAL
BACK PRESSURE REGULATOR
DA9 - DIRECT-ACTING, NEGATIVE BIAS DIFFERENTIAL
BACK PRESSURE REGULATOR
SECTION I
I. DESCRIPTION AND SCOPE
The Model DA8/9 are differential back pressure regultors used to control differential pressure between the upstream
(inlet or P1) pressure and a loading (PLoad) pressure to the spring chamber. Sizes for the DA8 are 1/2" (DN15), 3/4"
(DN20), 1" (DN25), 1-1/4" (DN32), 1-1/2" (DN40), 2" (DN50), 2-1/2" (DN65), 3" (DN80) and 4" (DN100). Sizes for
the DA9 are 1/2" (DN15), 3/4" (DN20), 1" (DN25), 1-1/4" (DN32), 1-1/2" (DN40) and 2" (DN50).With proper trim
uti li za tion, the unit is suitable for liquid, gaseous, or steam service. Models DA8/9 are available in a more common
“reverse” fl ow direction arrangement that is balanced (to outlet) and a “standard” fl ow direction arrangement that is
unbalanced, and does not require a dynamic seal. Refer to Technical Bulletin DA8/9-TB for design conditions and
selection rec om men da tions.
7-05
SECTION II
II. REFERENCES
Refer to Technical Bulletin DA8/9-TB and DAG-TB
for tech ni cal specifi cations of a Model DA8 or DA9
regulator.
SECTION III
III. INSTALLATION
CAUTION
For socket 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 recommended position is with the spring chamber (4)
upwards. In liquid service it is recommended that
the spring cham ber (4) be oriented downwards, and
that a cus tom er supplied and installed vent valve
be pro vid ed at the external sensing con nec tion to
bleed-off trapped gas/air under the di a phragm.
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 provide means for adjustment, operation, bypass, or
removal of the regulator. An isolation valve on the
loading line is not rec om mend ed.
ABBREVIATIONS
CCW – Counter Clockwise
CW – Clockwise
ITA – Inner Trim Assembly
4. An inlet pressure gauge should be located ap prox i mate ly ten pipe diameters upstream, and within
sight. A loading pressure (or differential pressure)
gauge is rec om mend ed.
5. Clean the piping of all foreign material including
chips, welding scale, oil, grease and dirt before
in stall ing the regulator. Strainers are rec om mend ed.
6. In placing thread sealant on pipe ends prior to
en gage ment, ensure that excess material is re moved and not allowed to enter the regulator upon
startup.
7. Flow Direction: Install so the fl ow direction match es
the arrow cast on the body or other markings such
as "in" and "out".
8. Precaution for Standard Diaphragm Construction:
The loading pressure should be lowered suffi ciently
prior to shutting off the process fl uid supply, to
prevent change to the diaphragm. The startup,
shutdown, and emergency operating procedures
should be reviewed to ensure that the loading
Page 2
pressure is less than 50% of the Diaphragm Proof
Rating (See table below) before shutting off the
process fl uid supply pressure. If the regulator is
specifi ed with a fully supported diaphragm, then
the diaphragm will withstand a loading pressure
equal to the Diaphragm Proof Rating for the fully
supported diaphragm.
9. Downstream Sensing Installation Considerations
– Internal or External Sensing:
a. The regulator may be installed with internal or
external sensing. Unless otherwise specifi 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, Paragraph H).
b. Reference DAG-TB, Table DAG-11 for recom-
mendations for applying external pressure
sensing.
c. For internal sensing, no external line is used.
For external sensing, use an external control
line. The line is connected from the port (1/4"
NPT) on the side of the body di a phragm fl ange
to an upstream pressure tap. The pressure
tap should be located a minimum of 10 pipe
diameters upstream of the regulator. It is
recommended that the upstream pressure
tap be located close to the point of use to
minimize the adverse affect of variable line
losses. A tubing outer diameter of 0.25 inch
is adequate for short sensing lines (less than
4 feet). Use 3/8" tubing or 1/4" Sch 40 pipe
for sensing lines of 5 to 50 feet.
d. For condensable vapors (i.e. steam) slope
the external sensing line downward 2 to 5
de grees to upstream 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
gases. (i.e., noncondensable fl uids)
CAUTION
The proof test pressure must not exceed the
diaphragm and body rating for the regulator.
A hydrostatic or pneumatic proof test is allowable under the following conditions for the standard diaphragm
construction: Uniformly pressurize the valve body inlet,
valve body outlet, and loading chamber to the lesser of
the Diaphragm Proof Rating or 1.5 times the Inlet Pressure Rating shown on the nameplate. For example, a 1"
DA8 with Cast Iron Body and Spring Chamber, Neoprene
Diaphragm (BC) has an Inlet Pressure Rating of 400 psig
CWP. The lesser pressure of 1.5X 400 psig = 600 psig
and the BC diaphragm proof rating of 750 psig is 600
psig. Therefore, uniformly pressurizing the DA8 to 600
psig is allowable. Take care to uniformly depressurize at
end of test.
Recommended Piping Schematic for
Differential Back Pressure Station
TABLE 1 – DIAPHRAGM PROOF RATING IN PSIG (BARG)
Body Sizes – inch (mm)
Diaphragm Material
Standard Diaphragm
Construction
BC, EPR 750 (51.7) 1200 (82.7) 450 (31.0) 800 (55.2)
HK, NBR, HK+TFE 300 (20.7) 1200 (82.7) 225 (15.5) 600 (41.4)
FK 500 (34.5) 1200 (82.7) 225 (15.5) 600 (41.4)
Elastomeric TFE 125 (8.6) 125 (8.6) 125 (8.6) 125 (8.6)
17-7 PH SST 500 (34.5) 1500 (103) N/A N/A
Be-Cu 300 (20.7) 750 (51.7) N/A N/A
302 SST 350 (24.1) 800 (55.2) N/A N/A
Inconel 718 500 (34.5) 1500 (103) N/A N/A
1/2" - 2" (DN15 - 50) 2-1/2" - 4" (DN65 - 100)
OPT-81 Full
Diaphragm Support
Standard Diaphragm
Construction
OPT-81 Full
Diaphragm Support
IOM-DA8/92
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IV. PRINCIPLE OF OPERATION
SECTION IV
1. Valve plug movements modulate the fl ow across
the valve seat to maintain the inlet pressure (P
equal to the sum of the differential pressure (∆PDIFF)
and the loading pressure (PLoad). The inlet pressure acting on the underside of the diaphragm
tends to lift the valve plug off the valve seat. The
loading pressure acting on the topside of the
diaphragm tends to close the valve plug against
the valve seat. The positive differential setting of
the range spring for the DA8 tends to close the
valve plug against the valve seat. The negative
V. STARTUP
1. Start with the block valves closed.
2. Relax the range spring by turning the ad just ing
screw CCW for the DA8 (viewed from above)
and CW for the DA9; a minimum of three (3) full
rev o lu tions. This reduces the ∆PDIFF (differential)
pres sure set point.
3. If it is a “hot” piping system, and equipped with
a bypass valve, partially open the bypass valve
to pre heat the system piping and to allow slow
ex pan sion of the piping. Check for proper steam
trap operation if installed. Closely monitor inlet
(up stream) pressure via gauge to ensure not
over-pres sur iz ing. NOTE: If no bypass valve is
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.
1)
SECTION V
differential setting of the range spring for the DA9
tends to lift the valve plug off the valve seat. The
inlet pressure tracks with changes to the loading
pressure. Each one psi increase or decrease in
the loading pressure produces a respective one
psi increase or decrease in the inlet pressure.
2. For a DA8/9 (single diaphragm) design, a com plete
diaphragm failure will cause the inlet process fl uid
to mix with the loading fl uid.
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.
9. Set the DA8 regulator set point (∆P
the ad just ing screw clockwise (CW) to increase
inlet pres sure or CCW to reduce inlet pressure.
The inlet (P1) pressure under these conditions
will approximate the desired dif fer en tial pressure
for the DA8. Turn the adjusting screw of the DA9
CCW to increase the negative differential setting
(i.e. CCW to change -10 psid to -20 psid) and
CW to decrease the setting. The negative differential setting is the difference between the loading pressure (PLoad) and the inlet (P1)pressure .
DIFF) by turning
CAUTION
Do not walk away and leave a bypassed reg u la tor
unattended!
5. Slowly open the inlet (upstream) block valve to
about 25% open, observing the inlet (up stream)
pres sure gauge. Determine if the reg u la tor is
fl owing. If not, slowly rotate the DA8/9 regulator
ad just ing screw CCW (viewed from above) until
fl ow begins.
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 is not pressurized. If the inlet (up stream) pressure exceeds the desired pres sure,
IOM-DA8/9
10. Pressurize the source of loading (PLoad) pres sure
and allow to fi ll the spring chamber cavity. Slightly
open the bleeder valve (item 3) to vent any air as the
spring chamber is fi lling with a liquid loading fl uid.
11. Develop system fl ow and pressure and readjust
set point as required to obtain desired response.
Per for mance should be checked at minimum and
maximum fl ow levels.
12. Install closing cap where applicable. The standard
regulator relies on a double o-ring rotary seal (item
34) around the non-rising adjusting screw.
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VI. SHUTDOWN
SECTION VI
CAUTION
Loading Pressure must be reduced before shutting
down the system pressure.
1. To prevent force imbalances and possible di a phragm failure, the loading pressure (PLoad)
should always be shutdown fi rst from its source
of pressure. Sys tems sequencing must ensure
this occurs.
2. When the loading pressure (PLoad) has been
shut down, the regulator inlet pressure (P1) should
de crease sub stan tial ly.
3. On systems with a bypass valve, and where sys tem pres sure is to be maintained as the regu la tor
SECTION VII
VII. MAINTENANCE
A. General:
1. The regulator may be serviced without
re mov ing the regulator from pipeline. The
regulator is designed with quick-change trim
to simplify maintenance.
2. Record the nameplate information to
requisition 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 recommended spare
parts. Only use original equipment parts sup plied by Cashco/KM for re build ing or re pair ing
regulators.
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 suplied as Spe-
cial Cleaning Option-55, -56, or -57, maintenance must include a level of cleanliness equal
to Cashco cleaning standards of #S-1134,
#S-1542, and #S-1589 respectively. Con tact
factory for details.
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 depending on
what dynamic sealing system the regulator is
using:
CAUTION
Do not walk away and leave a bypassed reg u la tor
un at tend ed.
is shut down, slowly open the bypass valve while
closing the inlet (upstream) block valve. Fully
close the inlet (up stream) block valve. (When on
bypass, the system pressure must be constantly
observed and manually reg u lat ed. Close the outlet (down stream) block valve.
4. If the reg u la tor and system are both to be shut down, slowly close the inlet (upstream) block
valve. Close the outlet (down stream) valve only
if regu la tor re moval is required.
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 ........
28 .....................All ............................................ Seat Disc
29 .....................All ...............................Seat Disc Washer
30 .....................All ......................................Seat Disc Nut
* Possible option isType NO Dynamic Side Seal for standard
fl ow only..
√ 2-1/2" thru 4" body sizes only and 1/2" - 1" with U-Cup.
A detailed view of the Dynamic Side Seal parts is shown
in Figure 1 on the next page.
Piston Ring Seal w/Metal Energizer
WARNING
SYSTEM UNDER PRESSURE. Prior to per form ing
any maintenance, isolate the reg u la tor from the sys tem and relieve all pressure. Failure to do so could
result in personal injury.*
* Includes external sensing connection if applicable.
IOM-DA8/94
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A
27.2
27.1
20
19
19
19
20
20
27.5
27.3
27.5
27.6
20
27.6
19
19
20
NOTE: Two
separate piston
rings per assembly.
Type CP— TFE Cap Dynamic Seal
Type PR — PRA Dynamic Seal
IOM-DA8/9
Type UC — U-Cup Dynamic Seal
Type NO — No Dynamic Seal
(Standard Flow Only)
Figure 1: Dynamic Side Seals
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B. Main Valve Disassembly:
11. Pull cage (19) up and out of body.
CAUTION D
SYSTEM UNDER PRESSURE. Prior to per form ing
any maintenance, isolate the reg u la tor from the
sys tem 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. The quick change trim allows for the disassembly of the regulator while installed in the
pipeline. Alternatively the maintenance can
be done in a shop area. NOTE: It is easier to
repair the regulator when mounted upright in
a horizontal pipe run compared to a vertical
pipe run or a regulator mounted with spring
facing down. The description hereafter will
assume shop disassembly.
4. Place the valve unit in a vise with the spring
chamber (4) upwards.
5. Relax range spring (6) forces by turning adjusting screw (1) CCW for DA8 (viewed from
above) until spring relaxes. Turn the adjusting
screw CW for the DA9 to relax the extension
load of the spring assembly (item 6). The easiest way to check this, is to carefully loosen the
locknut (item 2). If the adjusting screw (item
1) sinks into the chamber as the locknuts are
loosened, then the spring assembly is still
in extension. Turn the adjusting screw CW
to remove the extension. Fully remove the
locknuts.
6. Loosen the diaphragm fl ange bolts (11) and
nuts (12) uniformly.
7. Place matchmarks on body (23) and spring
chamber (4) fl anges. Com plete ly remove bolt-
ing (11,12) Re move the spring cham ber (4).
8. Remove spring follower (5) and range
spring (6.1) on DA8. Unthread the range spring
assembly (6.2) from the valve plug on DA9.
9. Grasp opposite edges of diaphragm (9) and
withdraw the ITA from within the cage (19).
Set the ITA aside.
10. Evenly loosen the cage cap screws (18) in
single revolution increments until fully loos ened; remove cage cap screws (18).
12. Remove o-ring cage seal (15).
13. Remove lower cage gasket (21).
14. For metal diaphragm constructions, remove
diaphragm gasket (37) from body (23) di a phragm fl ange.
15. Remove body (23) from vise. Solvent clean
all removed metal parts.
C. Disassembly of the ITA:
1. Body Sizes 1/2" – 2". (See Figures 2 thru 4):
a. Obtain two pieces of square-section
barstock with a 3/8"-7/16" dimension,
approximately 2 inches long.
b. Place plug (20) 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 lock nut
(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 op er at ing
conditions are ex ceed ing pressure drop
or temperature lim its.
f. For composition diaphragm con struc tion,
remove upper stem seal (14.1).
g. For metal diaphragm con struc tion, 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, ro tate end-
for-end, and resecure in vise using same
metal bars above.
k. Loosen seat disc 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 re mov al of seat disc
nut (30), seat disc washer (29), and seat
disc (28).
2. Body Sizes 2-1/2" – 4". (See Figure 6):
a. Place seat disc nut (30) into a vise with
the plug (20) oriented ver ti cal ly. Do NOT
over-tighten nut (30) in vise.
b. Place closed-end hex wrench onto
di a phragm locknut (7). Place sock et
IOM-DA8/96
Page 7
wrench on 3/4" hex upper end of plug
(20). Loos en diaphragm lock nut (7) while
holding plug (20) from ro tat ing by socket
wrench. Re move di a phragm lock nut (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
conditions are ex ceed ing pressure drop
or temperature limits.
e. Remove upper stem seal (14.1).
f. Remove lower diaphragm pusher 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. Rotate 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-
er at ing conditions are ex ceed ing pres sure,
pres sure drop, or temperature lim its.
Remove dynamic side seal (27) com po nents
from plug (20) for sizes 1/2" – 2", or from piston/guide bearing (13) for sizes 2-1/2" – 4".
Spe cial care should be taken 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 bear ing (13)
groove.
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 Re quire ments:
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 nec es sary,
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.
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.). Met al di a phragms should be replaced. These parts
MUST be re placed with fac to ry supplied new
parts.
2. Inspect the metal parts that will be reused. The
parts should be free of surface con tam i nants,
IOM-DA8/9
2. Position seat disc washer (29) next to seat
disc (28).
3. Engage seat disc nut (30) to secure washer
(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 metal bar-
stock pieces of VII.C.1.a., clamp the plug
(20) into a vise with the plug's (20) spindle
pointed upwards.
b. Using a torque wrench, tighten the seat
7
Page 8
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 threaded 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-tight en ing
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 dynamic side seal (27) (See
Figure 1): NOTE: Dynamic side seal (27) for
sizes 2-1/2"-4" is located on the pis ton/guide
bear ing (13). The dynamic side seal can be
in stalled on a work bench without need of a
vise.
a. Type CP:
1. Stretch o-ring energizer/seal (27.2)
over low er cir cum fer ence of pistonguide bear ing (13) or valve plug
(20), tak ing care not to “cut” o-ring
energizer/seal (27.4). Using thumbs,
work the o-ring energizer/seal (27.4)
up and into the groove of the pistonguide bear ing (13) or valve plug (20).
NOTE: A very slight amount of fl uid
and elas tomer compatible o-ring lubricant is rec om mend ed as an installation aid.
2. For metal diaphragm construction,
insert cam ber adjusting washer (17.2)
into cage (19) and allow to rest in the
bottom of the cage (19).
3. Position TFE cap seal (27.1) ring with
rectangular cross-section at end of
pis ton-guide bearing (13) or valve
plug (20). Stretch cap seal (27.1) over
lower end of piston-guide bear ing
(13) or valve plug (20) using thumbs
to work the cap seal (27.1) onto the
piston-guide bearing (13) or valve plug
(20). DO NOT USE A TOOL FOR THIS
STEP. Continue pressing cap seal
(27.1) up wards towards the groove
until the cap seal (27.1) “snaps” into
the groove of the piston-guide bearing
(13) or valve plug (20).
4. Position piston-guide bearing (13) or
valve plug (20) 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 piston-guide bushing (13)
or valve plug (20) into the cage (19),
simultaneously use fi ngers to lightly
press the cap seal (27.1) inwards into
the groove of the pis ton-guide bearing
(13) or valve plug (20) until the cap
seal (27.1) “slips into” the cage (19).
DO NOT USE TOOLS, LUBRICANT,
OR HEAVY FORCE TO EN GAGE
THE CAP SEAL (27.1) INTO THE
CAGE (19).
b. Type PR:
1. NOTE: A piston ring assembly (27.5)
consists of one metal corrugated energizer and two piston ring seals. Wrap
corrugated metal piston ring energizer
into the groove of piston-guide bearing
(13) or valve plug (20).
2. Spread a piston ring seal and slide
over lower circumference of pistonguide bearing (13) or valve plug (20).
Using thumbs and fi ngers, work the
piston ring seal into the groove of the
piston-guide bearing (13) or valve
plug (20). Repeat this procedure with
a second piston ring seal. Orient the
Z-cuts in the piston ring seals 180
degrees apart to minimize leakage
by the piston ring assembly.
3. Position piston-guide bearing (13) or
valve plug (20) over and into upper
end of cage (19) until the lower piston
ring seal touches the upper lip of the
cage (19). While gently applying force
to press the piston-guide bearing (13)
or valve plug (20) into the cage (19),
simultaneously use fi ngers to lightly
circumferentially press the piston
ring assembly (27.5) inwards into the
piston-guide bearing (13) or valve
plug (20) groove until the piston ring
assembly (27.5) “slips into” the cage
(19).
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
IOM-DA8/98
Page 9
that the u-cup seal (27.3) is oriented
with the cen ter-open-up wards as
shown in Fig ure 1, as the u-cup seal
(27.3) depends upon the P1-Inlet
Pres sure to pres sure ac ti vate the seal
for prop er seal ing ac tion.
d. Type NO:
1. For “standard” fl ow direction ap pli ca -
tions, it is not ab so lute ly required that
a dynamic side seal (27) be installed.
(When included with the dy nam ic seal
(27), better guid ing 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 por tion of di a phragm 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
ox y gen ser vice should use Fisher 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
in plug (20).
b. Place properly oriented piston/guide bear-
ing (13) over up per-end of plug (20) and
into po si tion on plug (20).
c. Place o-ring middle seal (14.2) over up-
per-end of plug (20) and into groove of
piston/guide bear ing (13).
9. Body sizes 1/2" thru 2".
Place new o-ring mid dle 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 diaphragm 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, be gin ning 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 di a phragm
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 lock nut (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": In sert
anti-seize coat ed 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-tight en
diaphragm cap screw (7) to 120-130
ft-lbs.
c. Body Sizes 2-1/2" thru 4": En gage di-
a phragm lock nut (7) to threaded post
of valve plug (20) and wrench-tight en
fi rmly. While restraining valve plug
(20) from rotating by torque wrench
on upper end 3/4" hex, use another
wrench to tighten di a phragm locknut
(7) to a torque of 180 - 200 ft-lbs.
16. This completes assembly of ITA; remove from
vise.
F. Main Reassembly:
1. Place body (23) in a vise.
2. Fit the o-ring cage seal (15) into its body (23)
groove.
3. For metal diaphragm construction, place
IOM-DA8/9
9
Page 10
seal ant (“Gasoila” or equal) on both sides of
diaphragm gasket (37) and position on body
(23) diaphragm fl ange.
4. Position properly oriented lower cage gasket
(21) onto lower shelf of cage (19).
5. Insert cage (19) into body (23) recess. Prop er ly
align all three 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, tak ing care
NOT TO “COCK” THE CAGE (19) IN THE
BODY. Torque the cage bolts (18) to 13-15
ft-lbs.
6. Lubricate and install o-rings (34) into grooves
on the adjusting screw (1).
7. Assembly of range spring and spring chamber
for DA8:
a. Lubricate the threads of adjusting screw
(1) then thread into the spring follower
(5).
The spring follower should be threaded
up adjusting the screw to within 3/8" of
the top threads (see sectional drawing,
fi gure 5.
b. Insert adjusting screw-spring follower into
spring chamber (4). NOTE: Milled slots in
spring follower must align with ribs in the
bore of the spring chamber. The top of
the adjusting screw must fi t in the center
hole of spring chamber. A light rap with
a wooden handle of a hammer may be
needed to fully install the adjusting screw
into the spring chamber.
c. Aligning match marks and bolt holes,
place spring chamber (4) over range
spring (6.1). If the spring chamber
fl ange reaches the body fl ange without
a gap, turn adjusting screw (1) CW 2-3
turns. Repeat this procedure until the
fl anges are approximately 1/8" apart.
Be sure that range spring is properly
seated into counterbore on spring follower.
8. Assembly of range spring assembly and spring
chamber for DA9:
a. Lubricate the threads of adjusting screw
(1), then thread into the range spring
assembly (6.2). The adjusting screw
should be threaded suffi ciently into the
range spring assembly to allow easy fi t-
ting of the spring chamber (see sectional
drawing, fi gure 6).
b. Thread the lower end of the range spring
assembly to the top of the valve plug. At
least three good threads of engagement
are required between the range spring
assembly and the valve plug. Back off
range spring assembly a fraction of the
turn to align the milled slots perpendicular
to the center line of the valve body. The
slots should now be ready to accept the
internal ribs of the spring chamber.
c. Aligning match marks and bolt holes
place spring chamber (4) over range
spring assembly (6.2). If the spring chamber fl ange reaches the body fl ange with-
out the adjusting screw passing through
the center hole of the spring chamber,
then remove the chamber. Holding the
range spring assembly stationary, turn
the adjusting screw CW 2-3 turns or
as required so the top of the screw will
pass through center holes of the spring
chamber. After the top of the adjusting
screw passes through the center hole of
the spring chamber, continue to turn the
adjusting screw CW until the adjusting
screw is fully fi tted into the spring cham-
ber. DO NOT allow the spring chamber
to rotate or the range spring assembly
may disengage from the valve plug.
d. Fit the locknut (2) to the top of the adjust-
ing screw. DO NOT over tighten the fi rst
locknut. The adjusting screw should turn
freely in the spring chamber. Lock the
second locknut against the fi rst locknut.
Again, check that the adjusting screw
turns freely.
9. 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” – 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. Relax range spring fully by rotating ad-
just ing screw CCW.
b. Apply 30 psig (2.1 Barg) pressure to the
valve outlet.
OR
Block the valve outlet and apply 30 psig
(2.1 Barg) under the di a phragm through
the 1/4" NPT (plugged) external pres-
sure sens ing connection on the valve
diaphragm fl ange.
c. Leave pressure on through tightening
of bolt ing (11,12).
IOM-DA8/910
Page 11
10. Evenly tighten the body bolting (11,12) in an
alternating cross pattern in one revolution
increments to the following torque value:
Body Size
in (mm)
1/2" - 2" (DN15-50) 30-35 (41-47)
2 1/2" - 4" (DN65-100) 45-50 (61-69)
Torque
ft-lb (N-m)
If supplied, remove pressure of previous Step 14.
G. Units with Supported Diaphragm Designs:
1. With composition diaphragm construction,
a supported diaphragm (9) construction is
des ig nat ed as Opt-81 High Inlet Pressure, and
comes with the highest range spring se lec tion
for sizes 2" and smaller.
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. Inboard Leakage Test (Seat + Dy nam ic Seal
Leakage).
a. Determine test pressure. If upper value
of range spring is less than 55 psig, use
test pressure of 5 psig less than upper
value of range spring. If upper value of
range spring is greater than 55 psig, use
test pressure of 50 psig.
b. While applying GN
or air pres sur iza tion
2
fl uid, engage adjusting screw inwards
until valve appears to be closed. Add one
additional revolution in wards to adjusting
screw.
c. Tube outlet to a beaker of water to ob serve
number of escaping gas bubbles.
3. Pressure Containment Test.
a. Pressurize inlet and outlet to 1.0 x Upper
Value of Range Spring or 30 psig with air
or GN2, whichever is higher.
b. Soap solution test all external leak points;
plugged connections, diaphragm fl ange,
di a phragm bolting and spring chamber
vent open ing.
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.
I. Pressure Testing:
1. If a hydrostatic pressure test is per formed,
pressure must be applied to all three of spring
chamber, inlet and outlet of body at the same
level.
CAUTION
DO NOT HYDROSTATICALLY TEST WITHOUT SPRING
CHAMBER PRESSURIZED. NOT ADHERING WILL DO
PHYSICAL INTERNALS DAMAGE THAT COULD REN DER THE UNIT INOPERABLE.
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.
IOM-DA8/9
11
Page 12
SECTION VIII
• 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 system.
C. Oversized regulator.
D. Unstable loading pressure.
B. Convert to external sensing (if necessary) and install an
orifi ce or needle valve in external sensing line.
C. Check actual fl ow conditions; resize regulator for minimum
and maximum fl ow; if necessary, replace with smaller regulator.
D1. Stabilize loading pressure; i.e. pump, control valve, etc.
D2. Air in loading piping. Vent spring chamber.
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 reoccurrence.)
3. Upstream pressure too high.
Possible Causes Remedies
A. Debris in trim preventing movement. A. Clean unit of debris.
B. Undersized regulator.
B. Check actual fl ow conditions; resize regulator for minimum and
maximum fl ow; if necessary, replace with larger regulator.
4. Diaphragm continually breaks (steam service regulators).
Possible Causes Remedies
A. Stem seals, which protect fl uorocarbon elastomer in
diaphragm assembly, may have deteriorated.
B. Diaphragm nut may not be torqued to proper value.
C. Diaphragm too stiff causing it to crack in service.
A. Replace with new stem seals.
B. Confi rm torque value in accordance with Section VII, paragraph
E-15.
C. Follow proper preforming and air pressure to underside of dia-
phragm techniques during diaphragm installation in accordance
with Section VII, paragraph F-9.
5. Diaphragm continually breaks (all regulators).
Possible Causes Remedies
A. Differential pressure across diaphragm may have
exceeded limits.
A. Reference limits as recorded in technical bulletin DA8/9-TB, as
well as where the various pressures are acting.
IOM-DA8/912
Page 13
6. Leakage at diaphragm fl ange.
Possible Causes Remedies
A. Body bolts not torqued high enough. A. Torque to proper value (see Section VI, paragraph F-10).
7. Leakage across seat or dynamic side seal.
Possible Causes Remedies
A. Contamination (debris) in regulator. A. Remove internals, clean and if necessary, replace regulator.
B. Oversized regulator.
B. Check actual fl ow conditions; resize regulator for minimum and
maximum fl ow; if necessary, replace with smaller regulator.
SECTION IX
IX. PARTS ORDERING INFORMATION
There are three methods to obtain parts ordering information/numbers. These methods are listed below, in order
of ease of entering. The least expensive method is to utilize parts in kits where possible.
METHOD A - USE OF PRODUCT CODE.
Step 1. If available, obtain the 18 character product code
number from:
a. The Bill of Materials (BOM) sheet attached
here in.
b. The metal tag attached to the regulator.
-
NOTE: Some regulators may not have the prod-
uct code lo cated on the metal tag.
Step 2. Identify which kits or parts are desired from the
fol low ing:
a. The BOM, or refer to the cross-sectional draw-
ings.
b. Standard maintenance parts for a basic regu-
la tor are identifi ed on the BOM. Kit “A” con tains
seal(s), diaphragm(s) and gasket(s). Kit “B”
contains trim re place ment parts plus seal(s),
diaphragm(s) and gasket(s).
Step 3. Contact your local KM Sales Rep re sen ta tive and
specify the product code number along with a
description of any parts not included in the kits.
Costs of re quired parts (and kits) can be given by
the Sales Rep re sen ta tive.
METHOD B - NO PRODUCT CODE AVAILABLE
- DISASSEMBLED REGULATOR.
Step 1. Determine all available information from regu la -
tor's metal tag.
a. Serial number (5-digit).
b. Regulator “Type” or “Model” number.
c. Size (may have to observe body tap).
d. Spring range.
e. Trim designation number (if available).
7 -
Step 2. Determine construction of trim and soft goods.
a. What is fl uid?
b. What material is trim?
c. What material are the diaphragms?
d. What material is the seat?
e. What materials are used for static seals and
dynamic seals?
Step 3. With the information from Steps 1 and 2 above,
contact your local KM Sales Rep re sen ta tive for
the proper iden ti fi ca tion numbers to use, and the
parts costs.
METHOD C - NO PRODUCT CODE AVAILABLE
- AS SEMBLED REGULATOR IN SERVICE.
Step 1. Determine all available information from metal
tag using Step 1, Method B.
Step 2. Contact your local KM Sales Rep with the above
information.
Step 3. Sales Representative will contact the factory
to de ter mine the original internal construction.
Fac tory will relay information to the Sales Rep re sen ta tive.
Step 4. Await the Sales Representative’s return contact
with the proper part numbers and cost.
IOM-DA8/9
13
Page 14
Figure 2
Model DA8
Composition Diaphragm
FTO – Reverse Flow Direction
IOM-DA8/914
Page 15
Item Numbers and Descriptions below apply to Figures 2, 3 and 4.
Item No. Description
1 Adjusting Screw
2 Adjusting Screw Lock Nut
3 Bleeder Valve Assembly
4 Spring Chamber
5 Spring Follower (Button) - DA8 Only
6 Range Spring - DA8 Only
6 Range Spring Assembly - DA9 Only
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
NOTE: Items 5 and 6 used on DA8 are replaced by Item 6, Range Spring Assembly used on DA9.
Item No. Description
19 Cage
20 Valve Plug
21 Lower Cage Gasket
23 Body
24 Lower Guide Bushing
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
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)
34 Adjusting Screw O-Ring (Qty=2)
99 Nameplate (Not Shown)
* Not required on 2" CS & SST Body Material.
Piston Ring Seal w/Metal Energizer
Figure 3
Model DA9
Composition Diaphragm
FTO – Reverse Flow Direction
IOM-DA8/9
15
Page 16
Figure 4
Model DA8/9 (Less Topworks)
Metal Diaphragm – Reverse Flow Direction
Item No. Description
7 Diaphragm Cap Screw
13 Piston/Guide Bearing
14 Stem Seals
14.1 Upper Stem Seal
14.2 Middle Stem Seal
14.3 Lower Stem Seal
15 Cage Seal
19 Cage
20 Valve Plug
21 Lower Cage Gasket
24 Lower Guide Bushing
28 Seat Disk
29 Seat Disk Washer
30 Seat Disk Nut
Cashco, Inc.
P.O. Box 6
Ellsworth, KS 67439-0006
PH (785) 472-4461
Fax (785) 472-3539
E-mail: sales@cashco.com
exportsales@cashco.com
Printed in USA IOM-DA8/9
Figure 5: Body Sizes
2-1/2" – 4", Composition Diaphragm
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