cashco DA6 Instruction manual

INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM) IOM-DA6
12-16
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 utilization, the unit is suitable for liquid, gaseous, or steam service. Typically installed in a more com-
mon “reverse” flow direction arrangement that is balanced (to outlet). Refer to Technical Bulletin DA6-TB for design
conditions and selection recommendations. (NOTE: This product was formerly identified as a Model D6; a Model
DA6 and D6 are one and the same product.)
MODEL DA6
DA6 - DIRECT-ACTING, PRESSURE LOADED
BACK PRESSURE REGULATOR
SECTION I
II. REFERENCES
Refer to Technical Bulletin DA6-TB and DAG-TB for
technical specifications of a Model DA6 regulator.
ABBREVIATIONS
CCW – Counter Clockwise
CW – Clockwise
ITA – Inner Trim Assembly
III. INSTALLATION
1. Install per direction of flow arrow indicated on
body, or "IN" and "OUT" markings.
2. Regulator may be rotated around pipe axis 360
degrees. For ease of maintenance, the recom-
mended position is with the cover dome (25)
upwards. In liquid service it is recommended that
the cover dome (25) be oriented downwards, and
that a customer supplied and installed vent valve
be provided at the external sensing connection
to bleed-off trapped gas/air under the diaphragm
during initial startup.
3. Provide space below, above, and around regulator
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
pipeline 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 specified,
the regulator is supplied by factory with internal
sensing. The regulator may be converted in
the field to external sensing. (See Section VII
Maintenance, Part H – Converting Internal/
External Sensing.)
b. Reference DAG-TB, Table DAG-12 for recom-
mendations 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 diaphragm flange to a
pressure tap upstream of the regulator. Use
1/4" (6.4 mm) or 3/8" (9.5 mm) outer diameter
tubing or 3/8" (DN10) pipe having an inner
diameter equivalent to schedule 40 pipe.
d. For condensable vapors (i.e. steam) slope the
external sensing line downward 2 to 5 degrees
to inlet piping to prevent water pockets, which
allows the diaphragm chamber to always be
self draining. The external sensing line may
be sloped upward for gas or liquid service; i.e.
non-condensibles.
SECTION III
SECTION II
CAUTION
Installation of adequate overpressure protection
is recommended to protect the regulator from
overpressure and all downstream equipment from
damage in the event of regulator failure.
ISO Registered Company

IOM-DA62
CAUTION
DO NOT HYDROSTATIC TEST THROUGH AN
INSTALLED UNIT; ISOLATE REGULATOR FROM
TEST. See Technical Bulletin DA6-TB, Table 1;
Maximum P1- Inlet Pressure levels for various
diaphragm materials by valve body size. Higher
pressures could cause internal damage. The name-
plate indicates the Inlet and Outlet pressure and
temperature ratings.
Recommended Piping Schematic
For Back Pressure/Relief Station
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.
IV. PRINCIPLE OF OPERATION
1. When a loading pressure – PLoad – is applied to
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 flow direction, and at 0.98–1.0 of the load-
ing pressure – PL– for the reverse flow direction.
NOTE: Fluctuations in the P2 – Outlet Pressure
will cause a deviation in pressure setpoint – PSP
– the “crack-open” pressure for the standard flow
direction. This deviation is compensated away for
the reverse flow direction.
2. Movement occurs as pressure variations register
SECTION IV
SECTION V
CAUTION
Do not walk away and leave a bypassed regula-
tor unattended!
on the diaphragm. The registering pressure is
the inlet, P1, or upstream pressure. The loading
pressure fluid opposes diaphragm movement. As
inlet pressure increases, the diaphragm pushes
up, opening the port; as inlet pressure decreases,
the loading pressure pushes the diaphragm down
and the port opening closes.
3. A complete diaphragm failure will cause the regu-
lator to fail closed if in the standard flow direction
variation, and tend to fail closed in the reverse
flow direction but with seat leakage.
4. Loss of loading pressure while inlet pressure is
imposed will cause valve to fail open.
3. Crack open manual bypass valve. Initially pres-
surize system while simultaneously controlling
P1pressure 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
expansion of the piping. Ensure proper steam
trap operation if installed. Closely monitor inlet
(upstream) pressure via gauge to ensure not
over-pressurizing. NOTE: If no bypass valve is
installed, extra caution should be used in starting
up a cold system; i.e. do everything slowly.
CAUTION
In the event of diaphragm failure, the process fluid
will mix with the loading fluid.
CAUTION
For welded installations, all internal trim parts, seals
and diaphragm(s) must be removed from regulator
body prior to welding into pipeline. The heat of
fusion welding will damage non-metallic parts if
not removed. NOTE: This does not apply to units
equipped with extended pipe nipples.

IOM-DA6 3
5. Open the outlet (downstream) block valve.
6. Slowly open the inlet (upstream) block valve to
about 25% open, observing the inlet (upstream)
pressure gauge. The regulator should be flow-
ing. Adjust the loading system pressure control
device setpoint pressure upwards until the main
valve flow 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.
8. Fully open inlet block valve.
9. Begin to slowly close the bypass valve if installed.
10. Develop system flow 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 flow to a minimum level and
observe pressure set point. Inlet pressure will
decrease from the set point of Step 10. The
maximum build in inlet pressure on increasing
flow should not exceed 10%. If it does, consult
factory.
VI. SHUTDOWN
1. Shutoff auxiliary loading pressure source.
2. Shutoff inlet block valve.
3. Shutoff the outlet block valve.
VII. MAINTENANCE
A. General:
1. The regulator may be serviced without remov-
ing the regulator from pipeline. The regulator
is designed with quick-change trim to simplify
maintenance.
2. Record the nameplate information to requisi-
tion spare parts for the regulator. The informa-
tion should include: size, Product Code, and
Serial Number.
3. Refer to Section VIII for recommended spare
parts. Only use original equipment parts sup-
plied by Cashco for rebuilding or repairing
regulators.
4. Owner should refer to owner's procedures for
removal, handling, cleaning and disposal of
nonreusable parts, i.e. gaskets, etc.
NOTE: On regulators originally supplied as
“oxygen clean” – Opt-55, maintenance must
include a level of cleanliness equal to Cashco
cleaning standard #S-1134.
5. The Inner Trim Assembly (ITA) is removed and
replaced in the body (23) as an assemblage of
parts. The ITA consists of the following parts:
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.
SECTION VII
4. Relieve the trapped upstream and downstream
pressure and loading pressure.
5. The regulator may now be removed from the
pipeline or disassembled for inspection and pre-
ventative maintenance while in-line.
A detailed view of the dynamic side seal parts
is shown in Figure 1 on the next page.
SECTION VI

IOM-DA64
Type CP— TFE Cap Dynamic Seal
Type PR — PRA Dynamic Seal
NOTE: Two
separate piston
rings per
assembly.
Figure 1: Dynamic Side Seals
Type UC — U-Cup Dynamic Seal Type NO — No Dynamic Seal

IOM-DA6 5
B. Main Valve Disassembly:
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 pipeline, it is recom-
mended that maintenance be done in a shop
when possible. The descriptions hereafter will
assume shop disassembly. Remove valve
from pipeline.
4. Place the valve unit in a vise with the cover
dome (25) upwards.
5. Loosen the diaphragm flange bolts (11) and
nuts (12) uniformly.
6. Place matchmarks on body (23) and cover
dome (25) flanges. Completely remove bolting
(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 increments until fully loos-
ened; remove cage cap screws (18).
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) dia-
phragm flange.
14. 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 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 "flats" 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
whether failed; determine if operating
conditions are exceeding pressure drop
or temperature limits.
f. For composition diaphragm construction,
remove upper stem seal (14.1).
g. For metal diaphragm construction, remove
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) approximately two (2) revolutions.
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).
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 dia-
phragm locknut (7). Place socket wrench
on 3/4" hex upper end of plug (20). Loosen
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
whether failed; determine if operating
conditions are exceeding pressure drop
or temperature limits.
WARNING
SYSTEM UNDER PRESSURE. Prior to performing
any maintenance, isolate the regulator from the
system and relieve all pressure. Failure to do so
could result in personal injury.

IOM-DA66
Figure 2: Body Sizes
1/2" – 1", Composition Diaphragm
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
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 loosened,
remove partial assembly (20, 27, 28, 29,
30) from vise. Complete removal 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 significant leakage was occur-
ring. If the dynamic side seal (27) shows signs
of significant leakage, determine if operating
conditions are exceeding pressure, pressure
drop, or temperature limits.
Remove dynamic side seal (27) components
from plug (20) for sizes 1/2" – 2", or from pis-
ton/guide bearing (13) for sizes 2-1/2" – 4".
Special care should be taken when using
“tools” to remove the components to ensure
that no scratches are imparted 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 discard the old “soft goods” parts (i.e.
o-rings, diaphragms, seals, etc.). Metal dia-
phragms should be replaced. These parts
MUST be replaced with factory supplied new
parts.
2. Inspect the metal parts that will be reused. The
parts should be free of surface contaminants,
burrs, oxides, and scale. Rework and clean
Figure 6: Body Sizes
2-1/2" – 4", Composition Diaphragm

IOM-DA6 7
the parts as necessary. Surface conditions
that affect the regulator performance are stated
below; replace parts that can not be reworked
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 finish on cylinder bore. No
“ledges” formed due to wear from
moving dynamic side seal (27).
2. 16 rms finish on its seating surface
for tight shutoff.
c. Lower guide bushing (24);
1. 16 rms finish on bore.
2. Max 0.015 inch (0.38 mm) clearance
between 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 dynamic
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 oxygen 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 re-
cess of lower end of valve plug (20) properly
oriented.
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
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 upwards,
place into a vise, grasping the seat disc nut
(30); tighten the vise lightly, only enough
to "hold" the plug (20) from rotating out of
the vise. Caution: Over-tightening the
vise can distort the seat disc nut (30) and
give bad final 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 rotating
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 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 lower circumference of valve
plug (20), taking 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 valve plug (20). NOTE: A very
slight amount of fluid and elastomer
compatible lubricant is recommended
as an installation 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 lower end of valve plug
(20) using thumbs to work the cap
seal (27.1) onto the valve plug (20).
DO NOT USE A TOOL FOR THIS
STEP. Continue pressing cap seal
(27.1) upwards towards 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
energizer (27.6) over lower circumfer-
ence groove of valve plug (20). Using
thumbs work the energizer (27.6) into
the valve plug (20) groove.
2. Spread a piston ring seal (27.5) and
slide over lower circumference groove
of valve plug (20), taking care not to

IOM-DA68
“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 procedure with a
second piston ring seal (27.5). Orient/
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
circumference 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
Pressure to pressure activate the seal
for proper sealing action.
d. Type NO:
1. For “standard” flow direction applica-
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” flow
direction always requires a dynamic
side seal (27).
7. Place fluid compatible thread anti-seize,
Locktite Corp., "Nickel Anti-Seize", or equal
on threaded portion of diaphragm cap screw
(7), sizes 1-1/4" and 1-1/2"; or, threaded post
portion of valve plug (20), sizes 1/2" – 1" and
2-1/2" – 4". (NOTE: Valves cleaned for oxy-
gen service should use fisher Scientific 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 upper-
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 diaphragm construc-
tion the “tongue and groove” “ridge” should
be on upper side, “flat” side downwards. For
metal diaphragm construction the “rounded”
surface of the lower diaphragm pusher plate
(10) should be on upper side, “flat” 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-
patible 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 lower wetted diaphragm (9) first.
14. Position upper diaphragm pressure plate (8)
on/over upper end of valve plug (20) prop-
erly oriented. For composition diaphragm
construction the "tongue and groove" "ridge"
should be on lower side, "flat" side upwards.
For metal diaphragm construction the "round-
ed" surface of the upper diaphragm pressure
plate (8) should be on lower side, "flat" side
upwards.
15. a. Body sizes 1/2" thru 1": Engage diaphragm
locknut (7) to threaded post portion 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 diaphragm 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 dia-
phragm locknut (7) to threaded post of
valve plug (20) and wrench-tighten firmly.
While restraining valve plug (20) from
rotating by torque wrench on upper end
3/4" hex, use another wrench to tighten
diaphragm locknut (7) to a torque of 180-
200 ft-lbs.

IOM-DA6 9
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
sealant (“Gasoila” or equal) on both sides of
diaphragm gasket (37) and position on body
(23) diaphragm flange.
5. Position properly oriented lower cage gasket
(21) onto lower shelf of cage (19).
6. Insert cage (19) into body (23) recess. Prop-
erly align all cage bolt (18) holes as there is
only one circumferential location possible for
this alignment. 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 touches the upper lip of the cage
(19). While gently applying force to press
the valve plug (20) into the cage (19), si-
multaneously use hand thumbs to lightly
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, LUBRICANT, 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 fingers to lightly
circumferentially press the first (lower)
piston ring seal (27.5) inwards into the
valve plug (20) groove until the first 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), simultaneously
use hand thumbs to lightly press the u-
cup 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, LUBRICANT, 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)
diaphragm bolt holes.
9. Aligning matchmarks and bolt holes, place
cover dome (25) onto body (23) diaphragm
(9) flange.
10. Reinstall all flange 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 tightened,
“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 diaphragm through
the 1/4" NPT (plugged) external pres-
sure sensing connection on the valve
diaphragm flange.
AND
c. Leave pressure on through tightening
of bolting (11,12).
11. Evenly tighten the body bolting (11,12) in an
alternating cross pattern in one revolution
increments to the following torque value:

IOM-DA610
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 protected against pressure reversal; i.e.
pressure 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 diaphragm
(9) support. Lower diaphragm support ring
(35) is captured by its location. Upon re-
moval of cover dome (25) and diaphragm
(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.
3. Body Sizes 2" and Smaller; Metal Diaphragm.
(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 diaphragm
(9) support and a groove for upper o-ring
diaphragm seal (65). Lower diaphragm
support ring (35) is captured by its loca-
tion. Upon removal of cover dome (25)
and diaphragm (9), the lower diaphragm
support ring (35) can be lifted upwards
and out of the body (23) cavity.
c. Dual o-ring seals (65) replace the dia-
phragm gasket (37) normally supplied with
standard metal diaphragm construction;
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).
b. Cover dome (25) is specially machined to
provide a surface for the upper diaphragm
(9) support.
c. When disassembling valve unit, after lower
diaphragm pusher plate (10) is removed,
access 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) flange bolt holes (only one
orientation possible) prior to engagement
and tightening of cage cap screws (18).
Torque screws to levels indicated in Sub-
Section 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 convert-
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 performed,
pressure must be applied to all three of cover
dome (25), inlet and outlet of body at the same
level.
2. Inboard Leakage Test (Seat + Dynamic Seal
Leakage).
CAUTION
DO NOT HYDROSTATICALLY TEST WITHOUT
COVER DOME PRESSURIZED. NOT ADHERING
WILL DO PHYSICAL INTERNALS DAMAGE THAT
COULD RENDER THE UNIT INOPERABLE.
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)
a. Release all loading pressure in cover
dome.
b. Pressurize inlet to 30 psig with air, GN2.
c. Tube outlet to a beaker of water to observe
number of escaping gas bubbles.
Inboard leakage path may be via plug/seat or
dynamic side seal.
3. Pressure Containment Test.
a. Pressurize inlet, outlet and cover dome
to 150 psig with air or GN2.

IOM-DA6 11
SECTION IX
SECTION VIII
Figure 7: Opt-81 — Composition Diaphragm
Construction, 2" and Smaller
Figure 8: Opt-81 — Metal Diaphragm
Construction, 2" and Smaller
b. Soap solution test all external leak points;
plugged connections, diaphragm flange
and diaphragm 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 device. See DAG-TB, Table DAG-10
for leakage classes.
VIII.PRESSURE LOADING
1. Loading pressure can be supplied using various schemes. Please reference LOADING SYSTEMS for the
schematics of these various schemes, including:
• pressure unloading using BPV
• pressure loading using PRV
• pressure loading using I/P transducer
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 process
may be causing difficulties.
The key to efficient 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 application and operating
conditions.
Figure 9: Opt-81 — Composition
Diaphragm, 2-1/2" – 4"

IOM-DA612
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 orifice or needle valve in external sensing line.
C. Oversized regulator C. Check actual flow conditions; resize regulator for minimum
and maximum flow; 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 reoccurrence.)
3. Upstream pressure too high.
Possible Causes Remedies
A. Supply pressure is down (confirm A. Increase supply pressure.
on pressure gauge).
B. Undersized regulator. B. Check actual flow conditions; resize regulator for minimum
and maximum flow; if necessary, replace with larger
regulator.
C. Pressure loading system pressure C1. Clean restriction or bleed orifices.
restricted. C2. Clean filter(s).
C3. Clean loading pressure control device.
D. Faulty loading pressure control device. D. Replace/repair loading pressure control device.
It is imperative the following information be provided by the customer:
• Fluid (with fluid properties)
• Range of flow rate
• Range of inlet pressure
• Range of outlet pressure
• Range of fluid 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 complaints along with possible causes and remedies.

IOM-DA6 13
4. Diaphragm continually breaks (steam service regulators).
Possible Causes Remedies
A. Stem seals (14) which protect A. Replace with new stem seals (14).
fluorocarbon elastomer in diaphragm
assembly may have deteriorated.
B. Diaphragm nut (7) may not be B. Confirm 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 flange.
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 flow conditions; resize regulator for minimum
operates directly next to seat. and maximum flow; 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-DA614
SECTION X
NEW REPLACEMENT UNIT:
Contact your local Cashco, Inc., Sales Represen-
tative 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.
–7–
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 reflects revision level for the product).
PARTS "KIT" for FIELD REPAIR:
Contact your local Cashco, Inc., Sales Represen-
tative 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” reflect 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 cross-
sectional drawings included in this manual for part
identification and selection.
A Local Sales Representative will provide quotation
for appropriate Kit Number, 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 accommodate the recommended
part(s) changes.

IOM-DA6 15
* Not required on 2" CS & SST Body Material.
See Figures 2 – 6 for alternate plug constructions.
‡‡ Recommended Repair Parts
For sizes 2-1/2" thru 4", see diaphragm/plug construction in Figure 6.
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
Model DA6
Composition Diaphragm
FTO – Reverse Flow Direction
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 specifications 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-DA616
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
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
* Not required on 2" CS & SST Body Material.
See Figures 2 – 6 for alternate plug constructions.
‡‡ Recommended Repair Parts
Model DA6
Metal Diaphragm
FTC – Standard Flow Direction

IOM-DA6 17
ATEX 94/9/EC: Explosive Atmospheres and Cashco Inc. Regulators
These valves satisfy the safety conditions according to EN 13463-1 and EN 13463-5 for equipment group IIG 2 c.
Caution: Because the actual maximum temperature depends not on the equipment itself, but upon the fluid temperature, a
single temperature class or temperature cannot be marked by the manufacturer.
Specific Precaution to Installer: Electrical grounding of valve must occur to minimize risk of effective electrical discharges.
Specific Precaution to Installer: Atmosphere vent holes should be plugged to further minimize the risk of explosion.
Specific Precaution to Maintenance: The Valve Body/ Housing must be regularly cleaned to prevent buildup of dust deposits.
Specific Precaution to Maintenance: Conduct periodic Continuity Check between Valve Body/ Housing and Tank to minimize
risk of electrical discharges.
Attention: When repairing or altering explosion-protected equipment, national regulations must be adhered to. For maintenance
and repairs involving parts, use only manufacturer's original parts.
ATEX requires that all components and equipment be evaluated. Cashco pressure regulators are considered components.
Based on the ATEX Directive, Cashco considers the location where the pressure regulators are installed to be classified
Equipment-group II, Category 3 because flammable gases would only be present for a short period of time in the event of a leak.
It is possible that the location could be classified Equipment-group II, Category 2 if a leak is likely to occur. Please note that the
system owner, not Cashco, is responsible for determining the classification of a particular installation.
Product Assessment
Cashco performed a conformity assessment and risk analysis of its pressure regulator and control valve models and their
common options, with respect to the Essential Health and Safety Requirements in Annex II of the ATEX directive. The details
of the assessment in terms of the individual Essential Health and Safety Requirements, are listed in Table 1. Table 2 lists all of
the models and options that were evaluated and along with their evaluation.
Models and options not listed in Table 2 should be assumed to not have been evaluated and therefore should not be selected
for use in a potentially explosive environment until they have been evaluated.
Standard default options for each listed model were evaluated even if they were not explicitly listed as a separate option in the
table. Not all options listed in the tables are available to all models listed in the tables. Individual TB’s must be referenced for
actual options.
When specifying a regulator that is to be used in a potentially explosive environment one must review the evaluations in Table 1
and 2 for the specific model and each and every option that is being specified, in order to determine the complete assessment
for the unit.
A summary of the models and options found to have an impact on ATEX assessment due to potential ignition sources or other
concerns from the ATEX Essential Health and Safety Requirements, are listed below.
1. The plastic knob used as standard on some models, (P1, P2, P3, P4, P5, P7, 3381, 4381, 1171, and 2171) is a
potential ignition source due to static electricity. To demonstrate otherwise, the knob must be tested to determine
if a transferred charge is below the acceptable values in IEC 60079-0 Section 26.14 (See items 25, 27, and 28 in
Appendix A). Until the plastic knob has been shown to be acceptable, then either the metal knob option, or a preset
outlet pressure option is required to eliminate this ignition source (See items 45 and 64 in Tables).
2. The pressure gauges offered as options on a few of the regulator models (DA’s, P1-7, D, 764, 521), use a plastic
polycarbonate window that is a potential ignition source due to static electricity. To demonstrate that the gauges are
not a potential source of ignition, the gauges would need to be tested to determine if a transferred charge is below
NOTICE
Only for Product Codes wherein hazard
category ATEX has been selected.

IOM-DA618
indicating the gauge is compliant with the ATEX Directive (See items 26, 27, and 28 in Appendix A). Until compliance
is determined, regulators should not be ordered with pressure gauges for use in potentially explosive environments.
3. Tied diaphragm regulators with outlet ranges greater than 100 psig should be preset to minimize the risk that improper
operation might lead to an outboard leak and a potentially explosive atmosphere (See item 6 in Table 1).
4. Regulators must be ordered with the non-relieving option (instead of the self-relieving option) if the process gas they are
to be used with is hazardous (flammable, toxic, etc.). The self-relieving option vents process gas through the regulator
cap directly into the atmosphere while the non-relieving option does not. Using regulator with the self- relieving option
in a flammable gas system could create an explosive atmosphere in the vicinity of the regulator.
5. Regulators with customer supplied parts are to be assumed to not have been evaluated with regard to ATEX and thus
are not to be used in a potentially explosive environment unless a documented evaluation for the specific customer
supplied parts in question has been made. Refer to Table 1 for all models and options that have been evaluated.
Product Usage
A summary of ATEX related usage issues that were found in the assessment are listed below.
1. Pressure regulators and control valves must be grounded (earthed) to prevent static charge build-up due to the flowing
media. The regulator can be grounded through any mounting holes on the body with metal to metal contact or the
system piping can be grounded and electrical continuity verified through the body metal seal connections. Grounding
of the regulator should follow the same requirements for the piping system. Also see item 30 in Table 1.
2. The system designer and users must take precautions to prevent rapid system pressurization which may raise surface
temperatures of system components and tubing due to adiabatic compression of the system gas.
3. Heating systems installed by the user could possibly increase the surface temperature and must be evaluated by the
user for compliance with the ATEX Directive. User installation of heating systems applied to the regulator body or
system piping that affects the surface temperature of the pressure regulator is outside the scope of this declaration and
is the responsibility of the user.
4. The Joule-Thomson effect may cause process gases to rise in temperature as they expand going through a regulator.
This could raise the external surface temperature of the regulator body and downstream piping creating a potential
source of ignition. Whether the Joule-Thomson effect leads to heating or cooling of the process gas depends on
the process gas and the inlet and outlet pressures. The system designer is responsible for determining whether the
process gas temperature may rise under any operating conditions. If a process gas temperature rise is possible under
operating conditions, then the system designer must investigate whether the regulator body and downstream piping
may increase in temperature enough to create a potential source of ignition.
The process gas expansion is typically modeled as a constant enthalpy throttling process for determining the temperature change.
A Mollier diagram (Pressure – Enthalpy diagram with constant temperature, density, & entropy contours) or a Temperature –
Entropy diagram with constant enthalpy lines, for the process gas, can be used to determine the temperature change. Helium
and hydrogen are two gases that typically increase in temperature when expanding across a regulator. Other gases may
increase in temperature at sufficiently high pressures.
Product Declaration
If the above issues are addressed by selecting options that do not have potential sources of ignition, avoiding options that
have not been assessed, and by taking the proper usage issue precautions, then Cashco regulators can be considered to be a
mechanical device that does not have its own source of ignition and thus falls outside the scope of the ATEX directive.
Cashco, Inc.
P.O. Box 6
Ellsworth, KS 67439-0006
PH [phone]
Fax. # [phone]
www.cashco.com
email: [email protected]
Printed in U.S.A. DA6-IOM
Cashco do Brasil, Ltda.
Al.Venus, 340
Indaiatuba - Sao Paulo, Brazil
PH [phone]
Fax. No.
www.cashco.com
email: [email protected]
Cashco GmbH
Handwerkerstrasse 15
15366 Hoppegarten, Germany
PH [phone]
Fax. No. [phone]
www.cashco.com
email: [email protected]