Cashco DA8 Differential - Manual

INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM) IOM-DA8/9
7-05
I. DESCRIPTION AND SCOPE
The Model DA8/9 are differential back pressure regultors used to control differential pressure between the upstream
(inlet or P
1
) pressure and a loading (P
Load
) 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.
MODEL DA8 & DA9
DA8 - DIRECT-ACTING, POSITIVE BIAS DIFFERENTIAL
BACK PRESSURE REGULATOR
DA9 - DIRECT-ACTING, NEGATIVE BIAS DIFFERENTIAL
BACK PRESSURE REGULATOR
SECTION I
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.
ABBREVIATIONS
CCW – Counter Clockwise
CW – Clockwise
ITA – Inner Trim Assembly
III. INSTALLATION
1. Regulator may be rotated around pipe axis 360
degrees. For ease of maintenance, the recom-
mended 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 pro-
vide 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 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
SECTION III
SECTION II
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.