Typical Signs Of Wear; Valve Plate - Danfoss APP W HC Series Operation Manual

Service guide | Trouble shooting guide for APP, APP S and APP S 674 pumps
6.

Typical signs of wear

Picture 1
Picture 2
Scratches
Picture 3
© Danfoss | DCS (im) | 2022.01

6.1 Valve plate

180R9410 | AQ282628894589en-000801 | IOM APP W HC 15-30 Pumps | 69
A normally worn valve plate has no marks/scratches but only a slightly
polished surface .
No scratches or marks should be felt . The surface must be flat and level .
A worn valve plate has scratches, and/or a polished surface . Even small
scratches will give a loss of flow .
A good way to identify a worn valve plate is to hold a straight knife edge
over the valve plate . When holding it up to the light, it will be possible to
see any space between the knife edge and the valve plate . See picture 3 .
If any light can be seen between the two arrows on the picture, the valve
plate is worn .
If any scratches or marks can be felt by running a fingernail over the surface,
the valve plate is worn .
The valve plate on picture 3 is highly damaged .