INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)
MODEL DA2
DIRECT-ACTING, POSITIVE BIAS DIFFERENTIAL
PRESSURE REDUCING REGULATOR
SECTION I
I. DESCRIPTION AND SCOPE
The Model DA2 is a differential pressure reducing regulator used to control differential pressure between downstream (outlet or P2) pressure and a loading (PLoad) pressure to the spring chamber. Sizes 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). With
proper trim uti li za tion, the unit is suitable for liquid, gaseous, or steam service. Refer to Technical Bulletin DA2TB for design conditions and selection recommendations.
SECTION II
II. REFERENCES
ABBREVIATIONS
IOM-DA2
11-13
Refer to Technical Bulletin DA2-TB and DAG-TB for
tech ni cal specifi cations.
SECTION III
III. INSTALLATION
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.
4. An outlet pressure gauge should be located ap prox i mate ly ten pipe diameters downstream, and
within sight. A loading pressure (or differential
pressure) gauge is rec om mend ed.
5. All installations should include a downstream
re lief device if the inlet pressure could exceed
the pressure rating of any downstream equipment or the maximum outlet pressure rating of
the unit.
CCW – Counter Clockwise
CW – Clockwise
ITA – Inner Trim Assembly
6. 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.
7. 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.
8. Flow Direction: Install so the fl ow direction
match es the arrow cast on the body.
9. If the loading pressure is not lowered suffi ciently
prior to shutting off the process fl uid supply,
then the diaphragm will be damaged with the
standard construction. The startup, shutdown,
and emergency operating procedures should be
reviewed to ensure that the loading pressure is
less than 50% of the Diaphragm Proof Rating
(See Table 1) 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.
PI
SRV
Outlet
@ P
2
Supply
@ P
1
(Shaded portion for steam/condensate systems)
Model 1000HP-1+6
Diffe re ntial
Bypass
Blowdown-Drain Blowdown-Drain
PI
10. 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 rec-
ommendations 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" NPT) on the side of the body di a phragm
fl ange (see port 5 in Fig. 5) to a pressure tap.
The pressure tap should be located a minimum
of 10 pipe diameters downstream of the regulator. It is recommended that the downstream
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 outlet piping to prevent water pock ets, which
allows the diaphragm chamber to always be
self draining. The external sensing line may
be sloped upward for liquids or gases.
CAUTION B
Installation of adequate overpressure pro tec tion
is recommended to pro tect the reg u la tor from
over pres sure and all down stream equip ment
from dam age in the event of regulator failure.
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 Outlet
Pressure Rating shown on the nameplate. For example, a 1" DA2 with Cast Iron Body and Spring Chamber,
Neoprene Diaphragm (BC) has an Outlet Pressure Rating of 400 psig CWP. The lesser pressure of 1.5X 400
psig = 600 psig and the BC diaphragm proof rating of
1250 psig is 600 psig. Therefore, uniformly pressurizing the DA2 to 600 psig is allowable.
Model DA2 & DA7 Differential
Pressure Reducing Regulator
CAUTION A
The proof test pressure must not exceed the
diaphragm and body rating for the regulator.
MAXIMUM DIAPHRAGM RATING *
NOTE: The below ratings may be further "derated" by limitations thru the Pressure Equipment Directive (97/23/EC-May '97).
BODY SIZE 1/2" - 2" (DN15-50) BODY SIZE 3" - 4" (DN80-100)
STD DIAPHRAGM
CONSTRUCTION
MAX P2 MAX P2 MAX
P
2
1250
(86.1)
450
(31.0)
700
(48.2)
125
(8.6)
1500
(103)
2
DIAPHRAGM
MATERIAL
BC, EPR
NBR
FKM, FKM+TFE, FK
3-ply (PTFE+FKM+PTFE)
METAL
Be-Cu
*Maximum setting of pressure safety device – safety relief valve or rupture disc.
**Not available for CI/CI, BRZ/CI, BRZ/BRZ, BRZ/CS, BRZ/SST, CS/CI & SST/CI constructions.
NA = NOT AVAILABLE
Recommended Piping Schematic for
Differential Pressure Reducing Station
TABLE 1
- psig (Barg)
**OPT-81 FULL DIAPHRAGM
SUPPORT
1250
(86.1)
1250
(86.1)
1250
(86.1)
125
(8.6)
NA NA
STD DIAPHRAGM
CONSTRUCTION
800
(55.1)
300
(20.6)
550
(37.9)
125
(8.6)
IOM-DA2
IV. PRINCIPLE OF OPERATION
SECTION IV
1. Valve plug movements modulate the fl ow across
the valve seat to maintain the outlet pressure
2) equal to the sum of the differential pressure
(P
(∆PDIFF) and the loading pressure (PLoad). The
outlet pressure acting on the underside of the
diaphragm tends to close the valve plug against
the valve seat. The outlet pressure acting on the
topside of the diaphragm tends to lift the valve
plug off the valve seat. The positive differential
setting of the range spring tends to lift the valve
plug off the valve seat. The outlet pressure tracks
V. STARTUP
1. Start with the block valves closed.
2. Relax the range spring by turning the ad just ing
screw CCW for the DA2 (viewed from above) a
minimum of three (3) full rev o lu tions. This reduces
the ∆P
DIFF (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 outlet
(down 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.
2. For a DA2 (single diaphragm) design, a com plete
SECTION V
7. Continue to slowly open the outlet (downstream)
8. When fl ow is established steady enough that the
9. Set the DA2 regulator set point (∆P
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 outlet pressure.
diaphragm failure will cause the outlet process
fl uid to mix with the loading fl uid.
block valve, especially when the downstream
piping system is not pressurized. If the outlet
(down stream) pressure exceeds the desired
pres sure, close the inlet block valve and go to
Step 2. Close bypass valve approximately 25%,
and re peat pro ce dure.
outlet (downstream) block valve is fully open, begin
to slowly close the bypass valve if installed.
DIFF) by turning
the ad just ing screw clockwise (CW) to increase
outlet pres sure or CCW to reduce outlet pressure. The outlet (P
2) pressure under these con-
ditions will approximate the desired dif fer en tial
pressure when loaded with PLoad for the DA2.
CAUTION C
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 outlet (down stream) pres sure gauge. Determine if the reg u la tor
is fl owing. If not, slowly rotate the DA2 regulator
ad just ing screw CW (viewed from above) until
fl ow begins. Slightly open the bleeder valve to
vent any air as the spring chamber is fi lling with
a liquid loading fl uid.
6. Continue to slowly open the inlet (upstream) block
valve until fully open.
IOM-DA2
10. Pressurize the source of loading (P
Load) pres sure
and allow to fi ll the spring chamber cavity. Slightly
open the bleeder valve 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 analyzed 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.
3
VI. SHUTDOWN
SECTION VI
CAUTION D
Loading Pressure should be lowered as described
in Section III, paragraph 9 before shutting down the
system pressure.
1. To prevent force imbalances and possible di a phragm failure of the standard diaphragm construction, the loading pressure (PLoad) should be
lowered until the loading pressure (P
Load) is less
than 50% of the diaphragm proof rating for the
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:
standard construction. System se quenc ing
must ensure this oc curs.
2. It is recommended that manual operation not be
attempted by a bypass valve during a shutdown.
3. When the outlet pressure (P
2) has been lowered
to 5 - 10 psig, the inlet (upstream) block valve
may be closed. The inlet pressure (P1) should
then decay to zero psig before the outlet (downstream) block valve is closed.
Item Dynamic
No. Seal Type Part Description
13 ..................... All ..........................Guide Bearing/Piston
14 .....................All ............................... StaticStem Seal †
14.1 ............... All ................... Upper Static Stem Seal †
14.2 ............... All ...................Middle Static Stem Seal †
14.3 ............... All ................... Lower Static Stem Seal †
15 .....................All ................................Cage O-ring Seal
16 .................CW,PW .............................................. Wiper
17.1 ..............CW,PW ................................. Wiper Washer
17.2 ........... OR,CP,PR ........ Camber Adjusting Washer *
17.3 ................. UC ..................................... Seal Retainer
19 ..................... All ................................................... Cage
20 ..................... All ...........................................Valve Plug
21 ..................... All ............................................Seat Ring
27 .....................All ............................. Dynamic Side Seal
27.1 ........... CP,CW ................................. TFE Cap Seal
27.2 ...........CP, CW ............................. O-ring Energizer
27.3 .............. UC .......... U-Cup Seal w/Metal Energizer
27.4 .............. OR ....................................... O-Ring Seal
27.5............PR,PW.....
* Metal Diaphragm Only.
† Comp. Diaphragm Only.
Piston Ring Seal w/Metal Energizer
A detailed view of the dynamic side seal parts is
shown in Figure 1 on the next page.
WARNING 1
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.
4
IOM-DA2
13
13
13
19
BODY
27.4
20
Type OR — O-Ring
Dynamic Seal
Piston Rings (2) w/Metal Energizer
19
27.2
19
27.1
27.5
20
Type CP— TFE Cap
Dynamic Seal
13
19
27.2
19
27.1
16
17.1
20
Type CW — TFE Cap
Dynamic Seal + Wiper
13
19
IOM-DA2
SECTION "A"
27.5
13
16
17.1
20
Type PW — PRA Dy nam ic
Seal + Wiper
Figure 1: Dynamic Side Seals
27.3
17.3
20
Type UC — U-Cup
Dynamic Seal
5
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