Norgren V74G Series Installation Instructions User Manual

V74g

ASSEMBLY
1. Lubricate o-ring (15), adjusting screw threads and tip of

adjusting screw (5, 7), and the outer circumference and
both sides of the thrust washer (4) with a light coat of
good quality o-ring grease.

2. Assemble the unit as shown on the exploded view.
3. Torque Table

Torque in

Item

N-m (Inch-Pounds)

2, 10 (Screw)

2,8 to 3,9 (25 to 35)

14 (Bottom plug)

2,3 to 3,4 (20 to 30)

WARNING

These products are intended for use in industrial

compressed air systems only. Do not use these products
where pressures and temperatures can exceed those listed
under Technical Data.

To provide overpressure protection for pneumatic

equipment, the flow capacity of the relief valve selected for
a specific application must be greater than the maximum
possible flow rate of the system connected to the inlet of
the valve.

The accuracy of the indication of pressure gauges can

change, both during shipment (despite care in packaging)
and during the service life. If a pressure gauge is to be
used with these products and if inaccurate indications may
be hazardous to personnel or property, the gauge should be
calibrated before initial installation and at regular intervals
during use.

Before using these products with fluids other than air,

for non industrial applications, or for life-support systems
consult Norgren.

TECHNICAL DATA
Fluid: Compressed air
Operating temperature*: -20° to +80°C (0° to +175°F)
* Air supply must be dry enough to avoid ice formation at

temperatures below 2°C (35°F).

Gauge ports:

1⁄4 PTF with PTF main ports
Rc1/4 with ISO Rc main ports
Rc1/8 with ISO G main ports

Materials:

Body: Aluminum
Bonnet: Aluminum
Valve: Aluminum and Nitrile
Elastomers: Nitrile
Bottom plug: Acetal

REPLACEMENT ITEMS
Service kit (includes items circled

on exploded view) ..............................................4384-700

Tamper resistant cover (knob adjustment only).......4355-51

PANEL MOUNTING DIMENSIONS
Panel mounting hole diameter: 52 mm (2.06")
Panel thickness: 2 to 6 mm (0.06" to 0.25")

INSTALLATION
1. Shut off air pressure. Install relief valve in air line -

●

with air flow in direction of arrow on body,

●

as close as possible to the device being serviced,

●

at any angle.

2. Connect piping to proper ports using pipe thread sealant

on male threads only. Do not allow sealant to enter
interior of relief valve.

3. Install a pressure gauge or plug the gauge ports.

WARNING

Do not cap or in any way restrict the outlet port of the

relief valve. Relief port must be open to atmosphere.

ADJUSTMENT
1. Turn relief valve adjustment clockwise to increase

pressure setting. Turn adjustment counterclockwise to
decrease pressure setting.

2. Always approach the desired pressure from a lower

pressure. When reducing from a higher to a lower
setting, first reduce to some pressure less than that
desired, then bring up to the desired pressure.

3. KNOB ADJUSTMENT. Push knob down to lock pressure

setting. Pull knob up to release. Install tamper resistant
cover (see Replacement Items) to make setting tamper
resistant.

4. T-HANDLE ADJUSTMENT. Tighten lock nut (8) to lock

pressure setting.

DISASSEMBLY
1. Shut off inlet pressure. Reduce pressure in inlet and

outlet lines to zero. Turn relief adjustment (1 or 7) fully
counterclockwise.

2. Relief valve can be disassembled without removal from

air line. Disassemble in general accordance with the item
numbers on exploded view.

CLEANING
1. Clean parts with warm water and soap.
2. Rinse and dry parts. Blow out internal passages in body

with clean, dry compressed air.

3. Inspect parts. Replace those found to be damaged.

IM-200.500

(4/98)

a subsidiary of IMI plc

* Relief valve can be adjusted to pressures in excess of, and less than, those specified. Do not use these units to control pressures outside of the specified ranges.

V74G

Installation & Maintenance

Instructions

Pressure Relief Valve

V74G -

★★★ - N★★

Thread Form
A....PTF
B....ISO Rc taper
G....ISO G parallel

Port
3 ....3/8"
4 ....1/3"
6 ....3/4"

Spring (Relief Pressure Range) *
F ....0,3 to 4 bar (5 to 60 psig)
M...0,3 to 10 bar (5 to 150 psig)
S....0,7 to 17 bar (10 to 250 psig)

Gauge
G....With
N....Without

Adjustment
K....Knob
T ....T-bar