Sensus 121 Series Installation And Maintenance Instructions Manual Download Page 14

14

Servicing – 1-1/2", 2", 2-1/2" 
General Instructions

1.

Make sure the regulator is entirely depressured before servicing.

2.

Carefully note location and position of all disassembled parts 
to be certain reassembly is correct. Inspect each one carefully 
and replace those that are worn or damaged or otherwise 
unsatisfactory.

3.

A moderate application of lubricant to O-Ring 

13

will help assure 

free stem movement and a tight seal. Similar application of 
lubricant to other O-Rings or Tetraseals will help assure their 
tightness. Do not use petroleum base lubricants.

4.

Bolted connections should be tightened evenly and firmly. 
Carefully tighten diaphragms into place. Bolts must be tight 
enough to prevent leakage, but not so tight that the diaphragm 
material is crushed or damaged.

5.

Upon completion of servicing, make certain that regulator 
installation is entirely free of leaks.

To Service Valve – 15

1.

Remove bolts 

38

and remove bottom cap 

37

and Tetraseal 

32

.

2.

Remove Retaining Ring 

16a

.   

3.

Remove both halves of valve holder 

16b

.

4.

Remove valve 

15

(wave washer 

14

will likely remove with the 

valve. Retain for reassembly. – To reassemble, replace parts
in reverse sequence.

To Install V-Port Wing – 12f

1.

Remove valve 

15

per assembly “To Service Valve - 

15

”.

2. 

Remove wave washer 

14

.

3.

Remove retainer 

12e

. It will not be used.

4.

Reinstall wave washer 

14

.

5.

Install V-Port wing 

12f

on stem with v-notch side against the 

wave washer and flat area exposed.

6.

Reassemble remaining parts in reverse sequence.

To Service Main Diaphragm – 11d

1.

Remove top cap 

1

, and release and remove adjustment 

3

On high pressure model remove cap 

1a

, release adjustment 

3a

and remove cover 

5

and button 

7a

. Mark or measure position 

of adjustment 

3

or 

3a

. Use this to return adjustment to this 

setting during reassembly.

2.

Remove spring 

9

.

3.

Remove bolts 

22

and upper case

21

.

4.

Rotate diaphragm assembly 

11

counterclockwise (this unscrews 

11h

from 

12d

) and remove.

5.

To disassemble diaphragm assembly, remove nut 

11a

Carefully note location and position of all parts to be certain 
of correct reassembly. Abrasive side of emery cloth washers face 
against diaphragm.
– To reassemble, replace parts in reverse sequence. 

Make sure the screwed connection between 11h and 12d is 
loose by approximately 1/2 turn.

To do this, carefully rotate 

diaphragm assembly 

11

clockwise until this screwed connection 

bottoms (do not jam it together). Then back-off diaphragm 
assembly 

11

counterclockwise approximately 1/2 turn. 

The 

11h

to 

12d

screwed connection must not be tight.

To Service Orifice – 19

1.

Remove valve 

15

per section “To Service Valve-

15

”.

2.

Remove main diaphragm assembly 

11

per steps 1 through 4 

“To Service Main Diaphragm-

11d

”.

3.

Remove seal diaphragm assembly 

12

per steps 3 and 4 under 

“To Service Seal Diaphragm-

12b

”.

4.

Remove Retaining Ring 

19a

.  

5.

Remove orifice 

19 

through top opening. 

To reassemble, replace parts in reverse sequence. 
(On reassembly, ensure that 

19a

is fully seated in its groove. 

Also, beveled edge of 

19a

faces downward toward bottom 

cap 

37

.)

To Service Seal Diaphragm – 12b

1.

Remove valve 

15

per assembly “To Service Valve-

15

”.

2.

Remove main diaphragm assembly 

11

per steps 1 through 4 

“To Service Main Diaphragm-

11d

”.

3.

Remove bolts 

25

and lower diaphragm case 

24

.

4.

Remove bolts 

29 

and centerpiece 

27

, and then remove seal 

diaphragm assembly 

12

.

5.

To disassemble 

12

, unscrew piston 

12a

from stem 

12d

Use a spanner wrench in notch in skirt of piston 
(this can also be done by inserting a standard 7/32" 
Allen wrench in the notch). 
To reassemble, replace parts in reverse sequence. 
Make certain that fabric side of seal diaphragm 

12b

faces 

upward and “rubber” side faces downward toward body. 
Do not pinch loop in seal  diaphragm 

12b

between ring 

33

and centerpiece

27

. Also, rounded edge of 

33

faces upward 

toward seal diaphragm 

12b

Periodic Inspection:

Regulators are pressure control devices with numerous moving 
parts subject to wear that is dependent upon particular operation 
conditions. To assure continuous satisfactory operation, 
a periodic inspection schedule must be adhered to with the 
frequency of inspections, determined by the severity of service 
and applicable laws and regulations.

Installation and Maintenance

Model 121 Regulators

Summary of Contents for 121 Series

Page 1: ...RM 1328 R10 Sensus Metering Systems Model 121 Regulators T H E G A S I N D U S T R Y Installation and Maintenance Instructions ...

Page 2: ...ust be strong 1 4 for 121 8 and 121 12 1 2 for 121 16 or larger steel tubing or pipe is preferred It must be well protected against breakage Regulator will open wide if the control line breaks 9 Make sure the regulator is correctly connected and adequately supported Ensure all pipe joints are tight Start Up A The inlet and outlet shutoff valves should both be closed If a by pass is used the by pas...

Page 3: ...cing adjustment button 3 or 3a 4 Adjust for the desired outlet pressure per previous section Set Point Adjustment 5 When adjustment is complete replace top cap 1 Screw it securely into place Failing to replace cap could result in unstable regulator operation 6 New spring range should be marked on regulator If old spring range appears on regulator it should be removed CAUTION The diaphragm case ven...

Page 4: ...121 8HP 6 psi to 10 psi Cadmium 143 16 021 08 outer 60 psi 8 White 143 16 021 13 inner 1 1 2 to 3 1 2 w c Red 143 16 021 03 main spring _ 120 10 021 10 counterspring 1 1 2 to 12 w c Maroon 121 42 021 00 main spring _ 120 10 021 10 counterspring 1 1 2 2 and 2 1 2 3 1 2 to 6 1 2 w c Red 2 O D 143 16 021 03 60 psi 12 Model 121 12 5 to 8 1 2 w c Blue 2 O D 143 16 021 04 6 to 14 w c Green 2 O D 143 16 ...

Page 5: ...psi to 3 psi Cadmium 143 16 021 08 40 psi 3 121 3 4 x 3 4 not available Back Pressure Regulator or Relief Valve Relief or Back Maximum Diaphragm Size Pressure Range Spring Color Part Number Case Pressure 3 to 5 1 2 w c Red Black 143 82 021 00 5 to 7 1 2 w c Blue Black 143 82 021 01 3 4 thru 2 1 2 6 to 13 w c Green Black 143 82 021 02 121 8 10 to 15 w c Blue 2 O D 143 16 021 04 10 psi 12 to 25 w c ...

Page 6: ...d c 2a 2 21a 1 4 NPT Control line connection 1 NPT Vent connection 6 3 4 1 1 1 4 Standard Differential Atmospheric or Zero Governors 16b 15 14 13 12 a b 11 a c h 3 1 35 22 23 21 24 25 26 27 29 37 38 32 19 16a c d f d 1 4 NPT Control line connection b 13 21a 2 45 1 NPT Vent connection 9 121 8 Standard 121 8 HP High Pressure Pipe Sizes inlet x outlet Screwed NPT 3 4 x 1 3 4 x 1 1 4 1 x 1 1 x 1 1 4 1...

Page 7: ...on 1 NPT Control line connection 7 h 11 13 1a 3a High Pressure Spring Adjustment 4 2a 2 21a a b c d e f g 27 25 26 24 23 22 21 45 21 9 7b 7a 5 1 NPT Vent connection 1 4 NPT Control line connection 121 8 High Pressure Back Pressure 3 4 1 1 1 4 Back Pressure Installation and Maintenance Model 121 Regulators 121 8 Back Pressure ...

Page 8: ...al Diaph Assembly Buna N 121 10 564 51 121 Seal Diaph Assembly Viton 121 10 564 52 12a Piston 121 10 053 51 12 12b Seal Diaphragm Buna N 121 10 364 50 12b Seal Diaphragm Viton 121 10 364 51 12c Plate 121 10 010 50 12d Stem Stainless Steel 121 10 016 53 13 O Ring Buna N 3 8 x 1 2 934007 O Ring Viton 3 8 x 1 2 902418 14 Wave Washer 905479 15 Molded Valve Buna N 45 50 Duro 121 10 311 50 Molded Valve ...

Page 9: ...Carefully note location and position of all parts to be certain of correct reassembly Abrasive side of emery cloth washers face against diaphragm To reassemble replace parts in reverse sequence Make sure the screwed connection between 11h and 12d is loose by approximately 1 2 turn To do this carefully rotate diaphragm assembly 11 clockwise until this screwed connection bottoms do not jam it togeth...

Page 10: ...tion and position of all parts to be certain of correct reassembly Abrasive side of emery cloth washers face against diaphragm To reassemble replace parts in reverse sequence Make sure the screwed connection between 11h and 12d is loose by approximately 1 2 turn To do this carefully rotate diaphragm assembly 11 clockwise until this screwed connection bottoms do not jam it together Then back off di...

Page 11: ...4 3a 5 7a 7b 9 21 45 21 22 23 24 25 26 29 1a 2a 2 29a 21a a b c e d f g h 11 High Pressure Spring Adjustment 27 1 NPT Vent connection 1 4 NPT Control line connection 121 12 Standard 121 8 Standard V Port Wing Option Standard Retainer Option 121 8 HP High Pressure 1 1 2 2 2 1 2 Standard Differential Atmospheric or Zero Governors 11 2 1 3 9 29a Fig 1 Adjustment 3 and Vent Connection 21b for Differen...

Page 12: ... g 11 h 25 26 27 29a 29 3a 4 5 7a 7b 9 21 45 21 22 23 24 High Pressure Spring Adjustment 1 NPT Vent connection 1 4 NPT Control line connection 121 12 Back Pressure 121 8 HP High Pressure Back Pressure 121 8 Back Pressure Installation and Maintenance Model 121 Regulators 1 1 2 2 2 1 2 Standard Differential Atmospheric or Zero Governors 12 Pipe Sizes inlet x outlet Screwed NPT 1 1 2 x 1 1 2 1 1 2 x ...

Page 13: ...gm Stud stainless steel 091 16 058 02 121 Seal Diaph Assembly Buna N 121 16 564 51 121 Seal Diaph Assembly Viton 121 16 564 52 12a Piston 121 16 053 51 12b Seal Diaphragm Buna N 121 16 364 50 12 12b Seal Diaphragm Viton 121 16 364 51 12c Plate 121 16 010 53 12d Stem stainless steel 121 16 016 53 12e Retainer 121 16 016 00 12f V Port Wings 121 16 012 52 O Ring Buna N 3 8 x 1 2 934007 13 O Ring Vito...

Page 14: ...and position of all parts to be certain of correct reassembly Abrasive side of emery cloth washers face against diaphragm To reassemble replace parts in reverse sequence Make sure the screwed connection between 11h and 12d is loose by approximately 1 2 turn To do this carefully rotate diaphragm assembly 11 clockwise until this screwed connection bottoms do not jam it together Then back off diaphra...

Page 15: ...f diaphragm assembly 11 counterclockwise approximately 1 2 turn The 11h to 12d screwed connection must not be tight To Service Seal Diaphragm 12b 1 Remove main diaphragm assembly 11 per steps 1 through 4 To Service Main Diaphragm 11d 2 Remove bolts 29 and centerpiece 27 then remove seal diaphragm valve and stem assembly 12 3 To disassemble 12 unscrew piston 12a from stem 12d Use a spanner wrench i...

Page 16: ...3 16 thick 2 1 3 9 45 21 22 23 24 25 26 27 28 13 a b c d f h 11 21a 1 4 NPT Control line connection 2 1 3 26 5 4 21a h f d c b a 11 13 a b c d 12 14 15a 15 16a 16b 17 18 19 19a 38 37 32 35 21 45 22 23 24 25 26 27 28 29 32 33 34 2a 8 7 9 10 1 4 NPT Control line connection 2a 1 3 9 45 21 a b c d f h 11 21a 22 23 24 28 27 26 25 1 NPT Vent connection 1 4 NPT Control line connection 3 4 Standard 3 4 Ba...

Page 17: ...sher substitute Poly U Disk 121 22 102 52 Retainer 121 22 103 50 17 Condensed Parts List 3 and 4 Illustration Description Part Number Number 3 Model 121 only 12a Piston 121 20 053 50 12b Seal Diaphragm Buna N 121 20 364 50 12 12b Seal Diaphragm Viton 121 20 364 51 12c Plate 121 20 010 50 12d Stem stainless steel 121 20 016 51 15 Molded Valve Buna N 45 50 Duro 121 20 311 50 Molded Valve Viton A 65 ...

Page 18: ...hat fabric side of seal diaphragm 12b faces upward and rubber side faces downward toward body Do not pinch loop in seal diaphragm 12b between ring 33 and centerpiece 27 Also rounded edge of 33 faces upward toward seal diaphragm 12b Make sure the screwed connection 11h and 12d is loose by approximately 1 2 turn To do this carefully rotate seal diaphragm assembly 12 clockwise until this screwed conn...

Page 19: ...uum The breaker inlet connects to a lesser vacuum to atmosphere or to a positive pressure The maximums for the positive pressure are 60 psi for 3 4 through 2 1 2 sizes 40 psi for 3 and 15 psi for 4 The vacuum breaker is normally closed and excess vacuum creates a valve opening movement which increases flow from the inlet and thereby relieves or breaks the excess All of the pipe sizes listed on Pag...

Page 20: ... 1 4 5 to 8 1 2 Blue Black 143 82 021 01 121 8 8 to 14 Green Black 143 82 021 02 12 to 20 Blue 143 16 021 04 18 to 30 Green 143 16 021 05 1 1 2 2 and 2 1 2 3 to 6 1 2 Red 143 16 021 03 121 12 5 to 8 1 2 Blue 143 16 021 04 8 to 14 Green 143 16 021 05 1 3 5 9 4 2 Vacuum Regulator Vacuum Regulators are used to maintain a certain negative pressure vacuum in enclosed spaces such as tanks vessels chambe...

Page 21: ...UTION There should be gas flow through the regulator during adjustment preferably small approximately 250 SCFH Do not adjust set point when there is no flow 3 When the desired set point is achieved retighten lock nut 12 and install seal cap 10 Make sure tetraseal 13 is not damaged Pilot Spring Change The outlet pressure range of the 121 RPC is determined by the pilot spring see table of Outlet Pre...

Page 22: ... service The maximum pressures that can be safely contained by model 121 diaphragm cases are as follows Model 121 8 25 psi Model 121 8HP 25 psi Model 121 12 20 psi Model 121 16 10 psi Safely contained means no leakage as well as no bursting Before using any of the above data make sure this entire section is clearly understood 22 Model 121 Regulators 121 PL Pressure Loaded The 121 PL is a pressure ...

Page 23: ... Model 121 Cast Iron Retaining Ring Plated Steel 1 1 2 thru 4 Model 121 Valve Plated Steel with Molded Buna N Soft Seal Valve Wing Plated Steel 3 Model 121 Valve Holder Plated Steel Retaining Ring and Wave Washer Stainless Steel O Rings and Tetraseals Buna N Adjustment Spring Ferrule Zinc Die Casting Bottom Spring Button Powdered Iron Plated Adjustment Screw 16 Diaphragm and H P Adjustment Spring ...

Page 24: ...30 days after Buyer discovers or should have reasonably discovered such purported defect or nonconformance and D shall only extend to Buyer and not to any subsequent buyers or users of the Goods Buyer shall provide Seller access to the Goods as to which Buyer claims a purported defect or nonconformance upon request by Seller Buyer shall at its own risk and expense promptly return the Goods in ques...

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