CVS 7970 Instruction Manuals

CVS 7970

High-Low Pressure

Each CVS 7970 is a self-contained unit containing

Instruction Manual

Head Office

Website: www.cvs-controls.com E-Mail: [e-mail]

Figure 1: CVS 7970 High-Low Pressure Pilot

Pilot

Introduction

This instruction manual includes the following
information for CVS 7970 High-Low Pressure Pilot:

1. D

escription

2. Piston Arrangement Changeover Instructions

3. Parts Information
O

nly persons qualified through training or experience
should install, operate and service this equipment. If
you have any questions regarding this product or this
manual, please contact your CVS Controls Sales
Representative before proceeding.

Description

The CVS 7970 is a versatile sensor that can be
programmed to detect and react to either increasing
pressure or decreasing pressure with an adjustab le
range of 2 to 10,000 PSI (.138 to 689.5 bar).

hen used within standard safety systems, a

W
pressure sensor monitors a specific media or
process pressure source for changes to the normal
operating range. Loss of pressure within the control
circuit will begin a shutdown sequence or trigger an
alarm, and pressure sensors can also indirectly
operate on/off flow control valves or pneumatic
driven pumps.

T

he CVS 7970 is a two position, three-way pilot with
universal ports (H, O, L), automatic reset (spring
return) and pressure balance spool.

3900 – 101 Street
Edmonton, Alberta, Canada T6E 0A5
Office: [phone]
Fax: [phone]

necessary components for four different piston
arrangements. Changeover instructions and
drawings are included in this manual. Parts which
are not installed in your current piston arrangement
are kept in an enclosed storage tube. Machined
within the piston housing of the CVS 7970 is a
convenient 1/8”–27 NPT Female process connection
and 1/2” NPT Male process connection.

Calgary Sales Office

Calgary, Alberta, Canada T2Z 3V6

3516 114 Avenue SE

Office: [phone]

Fax: [phone]

2

Table 1: CVS 7970 Specifications

Characteristic

Dimensions

Dimensions

1.750” diameter x 8.0” length

Working
Pressure

Process Pressure Inlet

10,000 PSI Maximum (689.5 bar)

Control Ports

125 PSI Maximum (8.62 bar)

Process Pressure Inlet

1/2”-14 NPT M and 1/8”-27 NPT F

Control Ports

1/4”-18 NPT F

Weight

3.5 lbs / 1.6 kg

Panel Hole Cutout Size

1 5/8” (39.81 mm)

M=Male, F=Female

Introduction continued

4. Loosen the lock nut and remove from the

Connections

One particular advantage of the CVS 7970 is its
adjustment range capability. Because of the
complete supplied components, there is no need to
purchase and store additional sets of matching
piston and spring components. The installation or
reorientation of the existing piston components
allows for an adjustment range capability of 2 to
10,000 PSI. This is especially convenient for remote
facilities which require changes to pressure settings
to match changes in process conditions.

The CVS 7970 is available in a High-Low
configuration using two pilots mounted and tubed to
a carbon steel or stainless steel manifold (Figure 8).
Your choice of 2-1/2” NPT process or gauge
connections are available. This design allows for
completely independent setting of the high and low
pilots spanning the range of 2 psi to 10,000 psi. This
configuration is available in Auto Reset (not shown)
or Manual Reset (shown, pg 8).

Piston Arrangement
Changeover Instructions

The information in this manual, including the parts
listings and piston detail drawings, will assist you in
completing the Piston Arrangement Changeover.

Caution: Consult and follow the established
safety procedures of your facility prior to
beginning disassembly of any CVS Control s
product. Ensure that all pressure is
exhausted from the system prior to
performing any service work. Failure to
remove the pressure from the system can
result in serious personal injury .

1. Isolate and depressurize the control system.

2. Disconnect the control circuit instrumentation
tubing from control valve, as well as the
monitored process connection from the
piston housing.

3. Where possible, remove the CVS 7970 from
the service location to perform the
changeover in a clean work environment.

adjusting cap. (See figure 2)

5. Gently relieve all spring tension by fully
unscrewing the adjusting cap. This allows
access to the storage tube.

6. Unscrew the piston housing from the valve
body.

7. Turn the piston housing upside down and tap
it gently on a flat, clean surface to remove
the piston arrangement. The pistons should
slide out easily.

8. Thoroughly clean the piston components,
including the piston housing and internal
bores, using warm water and a liquid
detergent. Do not use abrasive tools or
acidic cleansers. Dry all components with a
cloth or paper towel.

9. Lightly lubricate all components and seals,
and assemble the piston arrangement as
desired according to the enclosed detail
drawing.

10. When inserting the new piston arrangement
into the piston housing, apply even pressure.
Press evenly using both thumbs on the
piston’s outer edges for the insertion of the
1-1/8”, 1/2” and 3/16” piston arrangements.

11. For the 1/4” piston insertion, install the 1/4”
piston first, using a needle-nosed pliers.
Then press the other piston components into
place.

12. Lightly lubricate the threads of the piston
housing, body and spring housing. Be sure
to use a grease or medium appropriate for
stainless steel.

13. Reassemble the pressure pilot.

14. Adjust the pressure setting to the required
amount, and function test the pressure pilot.
When the desired setting is achieved, tighten
the lock nut securely against the adjusting
cap.

15. Connect the instrumentation tubing and the
pressure connection to the monitored
process.

16. Introduce pressure to the pressure pilot’s
control circuit and monitored process inlet.
Resume normal operation.

3

CVS 7970 High-Lo w Pres sur e Pilot

Key

Part Number

Qty.

Description

Material

1

CVS79710A

1

Adjusting Cap

Black Delrin

2

CVS79702A

1

5/16” Ball Bearing

Stainless Steel

3

CVS7911A

1

Spring Guide

Black Delrin

4

CVS7970A

1

Spring

302 Stainless Steel

5

CVS79712A

2

Lock Nut

Black Delrin

6

CVS79709A

1

Spring Housing

316 Stainless Steel

7

CVS79708

1

Stop Plate

316 Stainless Steel

8

CVS79704A

1

Body Housing

316 Stainless Steel

9

CVS79707A

1

Upper Stem

316 Stainless Steel

10

CVS79706A

1

Lower Stem

316 Stainless Steel

11

CVS79703A

1

Small Piston

316 Stainless Steel

12

CVS79705

1

Stop Washer

316 Stainless Steel

13

CS79702

1

Large Piston

316 Stainless Steel

14

CVS797014

1

Snap Ring

304 Stainless Steel

15

CVS79701A

1

Piston Housing

316 Stainless Steel

16

V-75-010

2

Seal

Viton Coated TFE

17

V-75-008

2

Seal

Viton Coated TFE

18

V-75-119

1

Seal

Viton Coated TFE

19

TFE-008

1

Back-Up Ring

Teflon

20

V-75-008

1

Seal

Viton Coated TFE

21

CVS79713A

1

1/4” Piston

316 Stainless Steel

22

V-75-006

1

Seal

Viton Coated TFE

23

TFE-006

1

Back-Up Ring

Teflon

24

TFE-012

1

Back-Up Ring

Teflon

25

V-75-012

1

Seal

Viton Coated TFE

CS7970-BK

1

Piston O-Ring Kit (Body Housing)

V-75-008 1 Seal

Viton Coated TFE

V-75-010 1 Seal

Viton Coated TFE

CVS7970-PK

1

Piston O-Ring Kit (Body Housing)

V-75-006 1 Seal

Viton Coated TFE

V-75-008 1 Seal

Viton Coated TFE

V-75-012 1 Seal

Viton Coated TFE

V-75-119 1 Seal

Viton Coated TFE

TFE-006 1 Back-Up-Ring

Teflon

TFE-008 1 Back-Up Ring

Teflon

TFE-012 1 Back-Up Ring

Teflon

Figure 2: Adjusting Cap / Storage Tube

Access

Table 2: Parts List

Seal Kits

4

Figure 3: CVS 7970 High-Low Pressure Pilot Assembly

5

Figure 4: 3/16 Piston Arrangement Enlarged Detail Drawing

For pressures from 5900 to 10,000 PSI (407 to 690 bar)

Key

Part Number

Qty.

Description

Material

11

CVS79703A

1

Small Piston

316 Stainless Steel

13

CS79702

1

Large Piston

316 Stainless Steel

14

CVS797014

1

Snap Ring

304 Stainless Steel

18

V-75-119

1

Seal

Viton Coated TFE

19

TFE-008

1

Back-Up Ring

Teflon

20

V-75-008

1

Seal

Viton Coated TFE

Figure 5: 1/4” Piston Arrangement Enlarged Detail Drawing

Key

Part Number

Qty.

Description

Material

11

CVS79703A

1

Small Piston

316 Stainless Steel

13

CS79702

1

Large Piston

316 Stainless Steel

14

CVS797014

1

Snap Ring

304 Stainless Steel

19

TFE-008

1

Back-Up Ring

Teflon

20

V-75-008

1

Seal

Viton Coated TFE

21

CVS79713A

1

1/4” Piston

316 Stainless Steel

22

V-75-006

1

Seal

Viton Coated TFE

23

TFE-006

1

Back-Up Ring

Teflon

For pressures from 1440 to 5900 PSI (99 to 407 bar)

6

Figure 7: 1-1/8” Piston Arrangement Enlarged Detail Drawing

Key

Part Number

Qty.

Description

Material

11

CVS79703A

1

Small Piston

316 Stainless Steel

12

CVS79705

1

Stop Washer

316 Stainless Steel

13

CS79702

1

Large Piston

316 Stainless Steel

14

CVS797014

1

Snap Ring

304 Stainless Steel

18

V-75-119

1

Seal

Viton Coated TFE

19

TFE-008

1

Back-Up Ring

Teflon

20

V-75-008

1

Seal

Viton Coated TFE

Figure 6: 1/2” Piston Arrangement Enlarged Detail Drawing

For pressures from 290 to 1440 PSI (20 to 99 bar)

Key

Part Number

Qty.

Description

Material

11

CVS79703A

1

Small Piston

316 Stainless Steel

13

CS79702

1

Large Piston

316 Stainless Steel

18

V-75-119

1

Seal

Viton Coated TFE

24

TFE-012

1

Back-Up Ring

Teflon

25

V-75-012

1

Seal

Viton Coated TFE

For pressures from 10 to 290 PSI (.689 to 20 bar)

7

Item Number Part Number

Description Qty.

1 CV S 7910A Adjusting Cap, Black Delrin 1
2 CV S 7920A 6/16" Ball Be ari ng, SST 1
3 CV S 7911A Spring Guide, Black Delrin 1
4 CV S 7970A Spri ng, 302 Stainless Steel 1
5 CV S 79712A Lock Nut, Black Delrin 2
6 CV S 79709A Spring Housing, 316 SST 1
7 CV S 79708A Stop Plate, 316 SST 1
8 CV S 79704A Body Housi ng, 316 SST 1

9 CV S 79707A Upper Stem, 316 SST 1
10 CV S 79706A Lowe r Stem, 316 SST 1
11 CV S 79730 Adapter, Low Pressure , 316 SST 1
12 CV S 79701LP Pi ston Housi ng, 316 SST 1
13 V-75-145 o-ring, Viton Coated TFE 2
14 CV S 79702LP Piston, LP, 316 SST 1
15 CV S 79731 Wiper Ring, Viton 1
16 V-75-010 Seal, Viton Coated TFE 2
17 V-75-008 Seal, Viton Coated TFE 2

Figure 8 – CVS Series 7970 Low Pressure Pilot – Adjustment 2 to 15 PSI, Assembly

CVS Series 7970 Low Pressure Pilot – Adjustment 2 to 15 PSI, Parts List

8

Figure 9: CVS Series 7970 High-Low Pressure Pilot Switch

Low Pilot

High Pilot

Low Pilot

High Pilot

Hi-Low Pressure Pilot - Manual Reset

Low Pressure Valve:
*Out Port To Valve

*Hi Port To Vent
High Pressure Valve:
*High Port To (air/gas) Supply (Max Supply Pressure 125 psi)

*Low Port To vent
Manifold:
*Either port for process

9

Instructional Schematic: Pressure Sensing Low – Decreasing (PSL)

Reducing Pressure
Inlet Pressure Absent

Unactuated - Monitored process control pressure has
Inlet Pressure Applied

Gaining Pressure

Actuated - Monitored process control pressure has
operation.

Normally Closed – Loss of Instrument (output) pressure, when sensed inlet pressure decreases below
the low pressure setting.

DECREASED below the Low Pressure Setting, or is absent.

INCREASED above the Low Pressure Setting. Normal

10

Instructional Schematic: Pressure Sensing High – Increasing (PSH)

Gaining Pressure

Inlet Pressure Applied

Unactuated - Monitored process control pressure is applied,
but is BELOW the high pressure setting. Normal operation.

Reducing Pressure

Inlet Pressure Applied

Actuated – Monitored process control pressure has

Normally Open – Loss in Instrument (output) pressure, when sensed inlet pressure increases above the
high pressure setting.

INCREASED ABOVE the high pressure setting.

11

Notes:

12

Rev 5 Feb 2016

Head Office

3900 – 101 Street

Webs ite: www.cvs-controls.com E-Mail: [e-mail]

CVS Controls Ltd. strives for the highest levels of quality and accuracy. The information included in this publication is presented f or

Edmonton, Alberta, Canada T6E 0A5
Office: [phone]
Fax: [phone]

Calgary Sales Office

3516 114 Avenue SE

Calgary, Alberta, Canada T2Z 3V6

Office: [phone]

Fax: [phone]

informational purposes only. CVS Controls Ltd. reserves the right to modify or change, and improve design, process, and
specifications without written notice. Under no circumstance is the information contained to be interpreted to be a
guarantee/warranty with regard to our products or services, applicability or use.
Selection, use and maintenance are the sole responsibility of the end user and purchaser. CVS Controls assumes no liability for the
selection use and maintenance of any product.

Printed in Canada