Cashco DA8 Differential User Manual download pdf

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 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.

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.

1 2 3 4 5 6 ... 15 16

Summary of Contents

Page 1 - MODEL DA8 & DA9

INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM) IOM-DA8/97-05I. DESCRIPTION AND SCOPEThe Model DA8/9 are differential back pressure regult

Page 2

IOM-DA8/910seal ant (“Gasoila” or equal) on both sides of diaphragm gasket (37) and position on body (23) diaphragm ﬂ ange. 4. Position properly orie

Page 3 - SECTION IV

IOM-DA8/91110. Evenly tighten the body bolting (11,12) in an alternating cross pattern in one revolution increments to the following torque value:

Page 4 - SECTION VII

IOM-DA8/9124. Diaphragm continually breaks (steam service regulators).Possible Causes RemediesA. Stem seals, which protect ﬂ uorocarbon elastomer in

Page 5 - NOTE: Two

IOM-DA8/9136. Leakage at diaphragm ﬂ ange.Possible Causes RemediesA. Body bolts not torqued high enough. A. Torque to proper value (see Section VI, pa

Page 6 - CAUTION D

IOM-DA8/914Figure 2Model DA8Composition DiaphragmFTO – Reverse Flow Direction

Page 7

IOM-DA8/915 Item No. Description 1 Adjusting Screw 2 Adjusting Screw Lock Nut 3 Bleeder Valve Assembly 4 Spring Chamber 5 Spring Foll

Page 8

Cashco, Inc.P.O. Box 6Ellsworth, KS 67439-0006PH (785) 472-4461Fax (785) 472-3539E-mail: [email protected] [email protected] in USA IOM-DA

Page 9

IOM-DA8/92pressure is less than 50% of the Diaphragm Proof Rating (See table below) before shutting off the process ﬂ uid supply pressure. If the reg

Page 10

IOM-DA8/93IV. PRINCIPLE OF OPERATION1. Valve plug movements modulate the ﬂ ow across the valve seat to maintain the inlet pressure (P1) equal to the

Page 11 - CAUTION

IOM-DA8/94SECTION VIVI. SHUTDOWN CAUTIONLoading Pressure must be reduced before shutting down the system pressure. CAUTIONDo not walk away and

Page 12 - SECTION VIII

IOM-DA8/95A27.227.120191919202027.527.327.527.62027.6191920Figure 1: Dynamic Side SealsType CP— TFE Cap Dynamic SealType PR — PRA Dynamic SealType UC

Page 13 - SECTION IX

IOM-DA8/961. Shut down the system in accordance with Section VI. 2. Disconnect the external sensing line, if in stalled.3. The quick change trim

Page 14 - Figure 2

IOM-DA8/97wrench 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

Page 15 - Figure 3

IOM-DA8/98disc 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 usi

Page 16 - Figure 5: Body Sizes

IOM-DA8/99that 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-In

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Cashco DA8 Differential User Manual

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