Cleaning and Inspecting DP Barrier Diaphragms

8/13/2019 Cleaning and Inspecting DP Barrier Diaphragms

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February 2012 ST 3000 Release 300 and SFC Model STS103 Users Manual 171

9.3 Inspecting and Cleaning Barrier Diaphragms

Background Depending on the characteristics of the process medium being

measured, sediment or other foreign particles may collect in the process

head cavity/chamber and cause faulty measurement. In addition, the

barrier diaphragm or diaphragms in the transmitters meter body may

become coated with a residue from the process medium. The latter is

also true for e

xternal diaphragms on flange mount and remote seal type

or heads from

spect

or diaphragms. For flange mount and remote seal

diaphragms, you may only need to run a purge line in the tank to rinse

ff the face of the diaphragm.

transmitters.

In most cases, you can readily remove the process head

the transmitters meter body to clean the process head cavity and in

the barrier diaphragm

o

Procedure The procedure in Table 53 outlines the general steps for inspecting and

cleaning barrier diaphragms. You may have to modify the steps to meet

your particular process or transmitter model requirements.

Table 53 Inspecting and Cleaning Barrier Diaphragms

Step Action

1 Close all valves and isolate transmitter from process. Open vent inprocess head to drain fluid from transmitters meter body, if required.

ATTENTION We recommend that you remove the transmitterfrom service and move it to a clean area before taking it apart.

2 Remove nuts from bolts that hold process head or heads to meterbody. Remove process heads and bolts.

Nuts

Processhead

O-ring

Centersection Process

head

O-ring

Bolts

Continued on next page


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ST 3000 Release 300 and SFC Model STS103 Users Manual February 2012172

9.3 Inspecting and Cleaning Barrier Diaphragms, Continued

Procedure, continued

Table 53 Inspecting and Cleaning Barrier Diaphragms, continued

Step Action

3 Remove O-ring and clean interior of process head using soft bristlebrush and suitable solvent.

4 Inspect barrier diaphragm for any signs of deterioration or corrosion.Look for possible residue and clean if necessary.

NOTE: If diaphragm is dented, has distorted convolutions or radialwrinkles, performance may be affected. Contact TAC forassistance.

5 Replace O-ring.

ATTENTION

We recommend that you install a new O-ring whenever a processhead is removed for cleaning.

The process head for a GP or an AP transmitter with single-headdesign has two O-ring grooves. A large one which is 2 in (50.8mm) in diameter and a small one which is 1.3 in (33 mm) indiameter as shown in the following illustration. On high-pressure,model STG180, GP transmitters, be sure to use a small O-ring inthe smaller/inner groove. On other models of GP and APtransmitters, use a large O-ring in the larger/outer groove. Neveruse both O-rings together.

Larger O-ringgroove forlower pressureapplications

Smaller O-ringgroove forhigh pressureapplications

22518

GP/AP Process Head

For process heads of a GP or AP transmitter with dual-headdesign, see detail illustration for differential pressure transmittersin Step 2.



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February 2012 ST 3000 Release 300 and SFC Model STS103 Users Manual 173


Procedure, continued

Table 53 Inspecting and Cleaning Barrier Diaphragms, continued

Step Action

6 Coat threads on process head bolts with anti-seize compound suchas Neverseize or equivalent.

7 Replace process head or heads and bolts. Finger tighten nuts.

8 Use a torque wrench to gradually tighten nuts to torque rating shownin Table 54 in sequence shown in following illustration. Tighten headbolts in stages of 1/3 full torque, 2/3 full torque, and then full torque.

1 3

24

Always tighten head bolts in

sequence shown and in these

stages:

1. 1/3 full torque

2. 2/3 full torque

3. Full torque

9 Return transmitter to service.

CAUTION Do not exceed the overload rating when placing thetransmitter back into service or during cleaning operations. SeeOverpressure ratings in Section 3 of this manual.



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ST 3000 Release 300 and SFC Model STS103 Users Manual February 2012174


Torque ratings Table 54 lists process head bolt torque ratings for given transmitter type.

B ng T

olti ypeMeter Body

Type

Process Head

Bolting Size5145255

Ca on Steel S dard

sp ified

(B7M Alloy Steel

Stainless Steel NACE

[CR Option]

5142557-002 and 003

(NACE [CR option]

Non-NACE [SS

option]

7-001 51452557-004

rbtan

ec

; no option [B7 option]) and

Stainless Steel)

7/16 x 14 UNC 20 N-m

[15.0 Lb-Ft +/- 0.8 Lb-Ft] [15.0 Lb-Ft +/- 0.8 Lb-Ft] [15.0 Lb-Ft +/- 0.8 Lb-Ft] [15.0 Lb-Ft +/- 0.8 Lb-Ft]

,3 +/- 1,0 N-m 20,3 N-m +/- 1,0 N-m 20,3 N-m +/- 1,0 N-m 20,3 N-m +/- 1,0 N-m

7/16 x 20 UNF NA NA 25,8 N-m +/- 1,3 N-m

[19.0 Lb-Ft +/- 1.0 Lb-Ft]

NA

51451864XXX5

(Model STD110

Transmitter[draft range]

only)M12 x 1.75 25,8 N-m +/- 1,3 N-m

[19.0 Lb-Ft +/- 1.0 Lb-Ft]

NA NA NA

M12 x 1.75 63,8 N-m +/- 3,4 N-m

[50.0 Lb-Ft +/- 2.5 Lb-Ft]

NA NA NA

7/16 x 20 UNF NA NA 63,7 N-m +/- 3,2 N-m

[47.0 Lb-Ft +/- 2.4 Lb-Ft]

NA

7/16 x 14 UNC 67,8 N-m +/- 3,4 N-m

[50.0 Lb-Ft +/- 2.5 Lb-Ft]

48,8 N-m +/- 2,4 N-m

[36.0 Lb-Ft +/- 1.8 Lb-Ft]

56,9 N-m +/- 2,8 N-m

[42.0 Lb-Ft +/- 2.1 Lb-Ft]

56,9 N-m +/- 2,8 N-m

[42.0 Lb-Ft +/- 2.1 Lb-Ft]

3/8 x 16 UNC 39,3 N-m +/- 2,0 N-m

[29 Lb-Ft +/- 1.5 Lb-Ft]

NA 39,3 N-m +/- 2,0 N-m

[29 Lb-Ft +/- 1.5 Lb-Ft]

39,3 N-m +/- 2,0 N-m

[29 Lb-Ft +/- 1.5 Lb-Ft]

M8 x 1.25 27,1 N-m +/- 1,4 N-m

[20.0 Lb-F

NA NA NA

t +/- 1.0 Lb-Ft]

51451864XXXXexcept

XXX5

(All STD 3000and SMV

3000Transmittersexcept

STD110)

5/16 x 18 UNC NA N-m

t]

NA 20,3 N-m +/- 1,0 N-m

[15.0 Lb-Ft +/- 0.8 Lb-Ft]

20,3 N-m +/- 1,0

[15.0 Lb-Ft +/- 0.8 Lb-F

Cleaning and Inspecting DP Barrier Diaphragms

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