Crane DM921 User Manual

CRANE BALANCING VALVES
DM921 & DMG921 DOUBLE REGULATING VALVE (DRV)
DM931 & DMG931 DA931 & DAG 931 VARIABLE ORIFICE DOUBLE REGULATING VALVE (VODRV)
DM941 & DMG 941 DA941 & DAG941 FIXED ORIFICE DOUBLE REGULATING VALVE (FODRV)
Pressure/Temperature Type 921 Type 931 & 941:
Rating: 16 bar at –10 to 120°C 16 bar at –10 to 120°C
13.4 bar at 180°C
End connections: Flanged valves (DM & DA):Flanges to BS EN1092-2 &
BS4504-3.1 Grooved valves (DMG & DAG): (for suitable pipe
sizes, see installation secton)
Pressure Test Valves: Crane P84 insertion test valves. P82 test valves, which
(931 & 941 ranges only) accept ‘Mechseal’ manometer adapters, are available as an
optional extra for temperatures up to 180°C
Flow direction: An arrow is cast on the side of the valve body to indicate the
direction of flow
Jointing Gaskets: Two flange gaskets are required for flanged end valves. IBC
(inside bolt circle) gaskets to BS EN 1514-1 are
recommended
Check List: Type 921: Instruction leaflet and Hex. Wrench.
Types 931 & 941: Instruction leaflet, Hex. Wrench & 2
pressure test valves
INSTALLATION, SETTING AND
MAINTAINANCE INSTRUCTIONS
FITTING PRESSURE
TEST VALVES
The pressure test valve with the red tag should
be fitted to the body tapping nearest to the
inlet end of the valve, and the valve with the
blue tag to the tapping nearest to outlet end of
the valve.
Use a thread sealant and do not exceed 1.1//2
turns from hand tight.
Type 931:
Remove two of the square headed plugs fitted
to the side tappings of the valve. It is
recommended that the pressure test valves are
fitted to the valve on the side of the flow direction
arrow and I.D. plate. They can be fitted on the
opposite side if access is limited without any
reduction in accuracy.
Type 941:
Remove the square headed plugs fitted to the top
of the valve and replace with the test valves
provided.

Crane DM921 Specifications

General

Brand	Crane
Model	DM921
Category	Control Unit
Language	English

Summary

Crane Balancing Valves

Fitting Pressure Test Valves

Instructions for fitting pressure test valves for Types 931 and 941, including specific details for each type.

Installation

General Installation Guidelines

Ensures valves are installed correctly in a straight pipe run, with correct gasket assembly and blanking flange for end-of-line service.

Type 941 Piping Requirements

Specifies straight piping lengths required for maximum flow measurement accuracy for Type 941 valves.

Valve Setting Indicator and Regulation

Valve Setting Indicator Description

Explains the micrometer style hand wheel's two scales for indicating valve settings.

Regulation Method (Type 921)

Describes how flow regulation is achieved by adjusting the micrometer hand wheel setting for Type 921.

Regulation Method (Type 931)

Explains flow regulation via hand wheel and deriving flow rate from pressure drop signals using charts.

Regulation Method (Type 941)

Details flow regulation and measurement using pressure drop charts, independent of hand wheel setting.

Setting Facility, Valve Isolation & Maintenance

Setting Facility Adjustment

Details how to retain a valve setting using memory stop screws and the required hex wrench.

Valve Isolation for High Pressures

Describes achieving tight shut-off at high pressures using closing bars/wrenches and provides torque guide.

Routine Maintenance (Gland Packing)

Instructions for tightening gland packing to resolve leaks, including tool sizes and precautions.

Pressure Equipment Directive Compliance

Directive 97/23/EC Classification

States valves are for non-hazardous liquids, classified as SEP, not CE marked, and require no declaration of conformity.