Ross Controls 2-2 WAY WITH PRESSURE RELEASE SERIES 27 User Manual

CHECK
VALVE

CHECK
VALVE

C1

C1

Pilot Pilot

V1 V1

OPERATING
VALVE

ExhaustExhaust

CYLINDER

B

C

A

Series 27 Pilot Operated Check Valves

• Can be used wherever a high-flow or remotely-controlled checking
function is needed.

• Can be used in a circuit to provide automatic stopping of a cylinder
in the event of the loss of electrical or pneumatic power.

• Also available with an automatic exhausting function, remote and
manual trapped pressure relief function, or solenoid dual pilot
operated check.

Single Pilot Operated Check Valve with

trapped pressure relief illustrated

Pressure Controlled Pilot Operated Check Valves

WITHOUT Trapped Pressure Relief Function

Valve Port Valve Model Avg. CV Dimensions inches (mm) Weight
Type Size Number

Type A Single

PO Check Valve

Ports: 1/4 through 1/2

Type B Single

PO Check Valve

Ports: 1/4 through 1½

Type C Dual

PO Check Valve

Ports: 3/8 through 1

1/4 2751A2908 2.2 1.5 (38) 3.6 (91) 2.0 (51) 2.3 (1.0)
A 3/8 2751A3908 2.9 1.5 (38) 3.6 (91) 2.0 (51) 2.3 (1.0)
1/2 2751A4915 3.2 1.5 (38) 3.6 (91) 2.5 (64) 2.3 (1.0)

1/4 2751A2903 2.3 3.6 (91) 3.8 (95) 3.1 (79) 1.3 (0.6)
B 3/8 2751A3901 3.8 3.6 (91) 3.8 (95) 3.1 (79) 1.3 (0.6)
1/2 2751A4902 4.0 3.6 (91) 3.8 (95) 3.1 (79) 1.3 (0.6)

1/2 2751A4905 7.7 4.6 (116) 4.4 (112) 3.1 (79) 2.3 (1.0)
B 3/4 2751A5903 9.0 4.6 (116) 4.4 (112) 3.1 (79) 2.3 (1.0)
1 2751A6901 9.0 4.6 (116) 4.4 (112) 3.1 (79) 2.3 (1.0)

1 2751B6904 24 6.7 (169) 6.5 (165) 4.1 (104) 6.0 (2.7)
B 1¼ 2751B7901 29 6.7 (169) 6.5 (165) 4.1 (104) 6.0 (2.7)
1½ 2751B8902 29 6.7 (169) 6.5 (165) 4.1 (104) 6.0 (2.7)

3/8 2768C3900 2.9 3.4 (89) 3.7 (94) 2.4 (61) 2.0 (0.9)
C 1/2 2768C4900 3.2 3.4 (89) 3.7 (94) 2.4 (61) 2.4 (1.1)
Dual 3/4 2768C5900 8.5* 4.4 (111) 4.1 (104) 3.0 (76) 3.8 (1.7)
1 2768A6900 8.5* 5.8 (147) 4.1 (104) 3.9 (99) 6.8 (3.1)

*Effective CV varies with load and pressure drop. Consult ROSS for specifics on your system.

(Fully open) A B C lb (kg)

TYPICAL APPLICATION

In the schematic diagram at the right, two single PO check valves (Type A or B) are
used in a typical cylinder circuit. Their function is to provide automatic stopping of
the cylinder if either electrical or pneumatic power is lost. This circuit can also be
used for jogging the cylinder as well as providing for an emergency stop.

In certain port sizes the two check valves could be replaced by just one Type C dual
PO check valve. The dual PO check valve contains the functions of two individual
checks in a single compact housing, and eliminates the need to connect externally
the inlet of one check to the pilot of the other.

STANDARD SPECIFICATIONS: For valves on this page.
Ambient/Media Temperature: 40° to 175°F (4° to 80°C).
Flow Media: Filtered air; 5 micron recommended.
Inlet Pressure: 15 to 150 psig (1 to 10 bar).
Signal Pressure: Must be equal to or greater than inlet.
Port Threads: NPT standard, BSPP. For BSPP threads add a

“D” prefix to the model number, e.g., D2751A2908.

2 © 2009, ROSS CONTROLS®.

IMPORTANT NOTE: Please read carefully and thoroughly all of the CAUTIONS on page 11.

PIPING NOTE FOR TYPE B VALVES

Port 1 should be piped to the cylinder,

and port 2 to the operating valve.

All Rights Reserved.

Pressure Controlled Pilot Operated Check Valves

B

A

C

WITH Trapped Pressure Relief Function

Air pilot or solenoid pilot operated check valves with trapped pressure relief can be used to control
a pneumatic cylinder in several important ways. For example:

• Maintaining a cylinder (horizontal or vertical) in a stationary position upon loss of electrical power.

• Jogging a cylinder.

• Relieving pressure trapped between check valve and cylinder.

Correct installation of a dual check valve is essential. It should be mounted as close to the cylinder
as possible. Minimizing the air volume by keeping the air lines short will reduce cylinder “bounce,”
and help to give the best performance.

Valve Port Valve Model Avg. CV Dimensions inches (mm) Weight
Type Size Number

(Fully open) A B C lb (kg)

3/8 2751B3922 2.6 1.65 (41.9) 3.57 (90.6) 2.2 (55.9) 1.8 (0.8)
A 1/2 2751B4922 2.8 1.65 (41.9) 3.57 (90.6) 2.2 (55.9) 1.8 (0.8)

Remote

3/4 2751B5917 9.2 4.3 (110) 4.2 (107) 2.2 (56) 2.9 (1.3)

3/8 2751B3920 2.6 1.65 (41.9) 3.47 (88) 2.2 (55.9) 1.8 (0.8)
A 1/2 2751B4920 2.8 1.65 (41.9) 3.47 (88) 2.2 (55.9) 1.8 (0.8)

Manual

3/4 2751B5919 9.2 4.3 (110) 4.2 (107) 2.2 (56) 2.9 (1.3)

3/8 2768D3901 2.9 3.6 (91.4) 3.64 (92.4) 2.6 (66.1) 3.5 (1.6)
D 1/2 2768D4901 3.2 3.6 (91.4) 3.64 (92.4) 2.6 (66.1) 3.5 (1.6)
Remote 3/4 2768D5901 8.5* 4.98 (126.5) 4.24 (107.7) 3.4 (86.4) 5.2 (2.3)
1 2768D6901 8.5* 4.98 (126.9) 4.24 (107.7) 3.4 (86.4) 8.8 (4.0)

3/8 2768D3904 2.9 3.6 (91.4) 3.6 (91.4) 2.6 (66.1) 3.2 (1.4)
D 1/2 2768D4904 3.2 3.6 (91.4) 3.6 (91.4) 2.6 (66.1) 3.5 (1.6)
Manual 3/4 2768D5904 8.5* 4.8 (122) 4.24 (107.7) 3.4 (86.4) 5.2 (2.3)
1 2768D6904 8.5* 4.8 (122) 4.24 (107.7) 3.4 (86.4) 8.8 (4.0)

*Effective CV varies with load and pressure drop. Consult ROSS for specifics on your system.

Type A Single

PO Check Valve

(Remote Trapped

Pressure Relief)

Ports: 3/8 through 3/4

B

Ports: 3/8 through 3/4

C

Type D Internal Pilot Dual

PO Check Valve

(Remote Trapped

Pressure Relief)

Ports: 3/8 through 1/2

C

A

Type D Internal Pilot

Dual PO Check Valve

B

Ports: 3/8 through 1/2

A

C

Type A Single

PO Check Valve

(Manual Trapped

Pressure Relief)

C

(Manual Trapped
Pressure Relief)

B

A

B

A

Solenoid Controlled Pilot Operated Check Valves

Type E Solenoid Pilot

Dual PO Check Valve

24 volts DC 24 volts DC
Valve Port Avg. DIN 3-Pin Mini 3-Pin Mini 4-Pin Micro Dimensions inches (mm) Weight

Type Size C

Connector Connector Connector Connector A B C lb (kg)

V

3/8 2.9 2778C3900 2778C3901 2778C3902 2778C3904 3.60 (91.4) 5.67 (144) 2.60 (66.1) 4.0 (1.8)
E 1/2 3.2 2778C4900 2778C4901 2778C4902 2778C4904 3.60 (91.4) 5.67 (144) 2.60 (66.1) 4.2 (1.9)
3/4 8.5* 2778C5900 2778C5901 2778C5902 2778C5904 4.98 (126.5) 6.77 (172) 3.40 (86.4) 6.1 (2.8)
1 8.5* 2778A6900 2778A6901 2778A6902 2778A6904 4.98 (126.5) 6.77 (172) 3.40 (86.4) 6.1 (2.8)

*Effective CV varies with load and pressure drop. Consult ROSS for specifics on your system.

Connector Wiring

3

1

SOLENOID

2

SOLENOID

DIN

Connector

AC Mini

Connector

STANDARD SPECIFICATIONS: For valves on this page.

INTERNAL PILOT MODELS:

Ambient/Media Temperature: 40° to 175°F (4° to 80°C).
Inlet Pressure: 15 to 150 psig (1 to 10 bar).

SOLENOID PILOT MODELS:

Solenoids: AC or DC power.
Standard Voltages:

24 volts DC; 3-pin Mini and 4-pin Micro connectors.

100-110 volts, 50 Hz; 100-120 volts, 60 Hz;

DC Mini

Connector

Power Consumption: 8 VA inrush, 6 VA holding on AC; on DC 4.5

watts with 4-pin Micro connector, 60 watts with 3-pin connector.

Ambient Temperature: 40° to 120°F (4° to 50°C).
Media Temperature: 40° to 175°F (4° to 80°C).
Flow Media: Filtered air; 5 micron recommended.
Inlet Pressure: 30 to 150 psig (2 to 10 bar).
Signal Pressure: Must be equal to or greater than inlet.
Port Threads: NPT standard, BSPP. For BSPP threads add a “D”

prefix to the model number, e.g., D2778D3900.

3

1

2

Ports: 3/8 through 1

Common

SOLENOID

+ 24VDC

DC Micro

Connector

4

1

2

3

+ 24 VDC

SOLENOID

Common

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