Spare Parts

Sl.No. Description Qty.
1 Body 1
2 Sleeve 1
3 Spool 1
4 Capscrew 4
5 End Plug 1
* 6 O' Ring 1
7 Bonded Seal 1
8 Plug Socket Head 1
9 Steel ball 1
* 10 O' Ring 1
11 Spring Pad 1
12 Spring 1
Sl.No. Description Qty.
13 Spring Pad 1
14 Spring 1
15 Spring Casing 1
* 16 O' Ring 1
17 Adjusting Screw 1
18 Top Nut 1
19 Check Nut 1
20 Cap 1
21 Cerclip External 1
* 22 O' Ring 4
23 Spring Dowel 1

Note : * Recommended Spares
While ordering the spares give complete details of Model Code punched on the valve body.


Maintenance Manual


Operation and Maintenance Instructions :

Polyhydron make Direct Acting Pressure Reducing valves are reliable hence require very little attention from user. However it is necessary that following points must be kept in mind while storage, operation, commissioning and maintenance.

Storage :

The valve needs to be well lubricated to prevent the spool from getting stuck up in valve body due to possible corrosion. It should be properly covered to protect from dust/dirt.

Operation :

Direct Acting Pressure Reducing valves are designed to limit a secondary circuit to a pressure lower than the main relief valve setting.

It is basically a variable orifice, the opening or closing of which is controlled by a (metering) spool. The pressure at outlet is sensed on the spool end opposite the spring through a pilot line. When the outlet pressure exceeds the spring setting, the spool moves towards a more closed position, thereby reducing the down stream pressure.

For remote sensing (optional), a pilot line is connected through port B to the spool end opposite to the spring.

When the pressure at A port exceeds the spring setting, the spool moves connecting the port A to the tank port, thus relieving the excess pressure.

Commissioning :

The things that should be attended to during commissioning are as follows:

The inlet line should be connected to the port P of the valve and the outlet to the port A.

For remote controlling (optional) the pilot line is to be connected to the port B. Tank port must be drained.

Cap screws and the corresponding tightening torque should be as mentioned in the data sheet.

Maintenance :

To enhance the proper working of the valve it is necessary to attain the following points. :

The oil must be of prime quality and clean as per ISO code 16/13.

Contaminated oil may lead to the wear of the spool there by increasing clearance between the pilot piston and housing. This results in the improper working of the valve.

The oil temperature must be within the specified range i.e. -20 C to +70 C.


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Subject to revision.

Regd. office & Works :
78-80, Machhe Industrial Estate, Machhe, Belgaum - 590 014. Karnataka, INDIA. 
Phone :
+91-0831-2411001.  Fax : +91-0831-2411002 ,  
E-mail : ,  Website :


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Polyhydron Pvt. Ltd, Belgaum, India.

Updated on February 04, 2015 03:05 pm .