60.Compressor valve overhauling

1. Stop the compressor.

2. Remove the fuses and put a tally “MEN AT WORK”

3. Shut the compressor outlet valve.

4. Make sure it is depressurized and keep the drain open.

5. Open the valve cover and clean the valve pocket for any carbon

deposits.

6. Pull the valve out form the pocket and remove the gasket.

7. Remove the split pin and open the castle nut.

8. Dismantle all the parts and soak in kerosene or clean diesel oil.

9. Clean all the parts with a soft brush. In case of a hard deposit a copper

plate of washer can be used for the scraping action.

10. Check the valve plates and the valve seats for any damage and cracks.

If any signs of fatigue cracks on the valve plates are present, then the

valve plate must be replaced with new ones. The valve plate must never

be turned over and used as it can lead to fatigue failure.

11. The valve plate and the valve seat must be separately lapped on a

surface plate using fine and extra fine grinding paste.

12. Thereafter all the parts must be washed with diesel and cleaned with

compressed air.

13. The valve should then be assembled, with the lapped surface of the

valve plate and the valve seat facing each other.

14. After the assembly of the valve the operation of the valve should be

checked by a soft wooden stick.

15. After the overhaul the valves have to be checked for leakage. The

space above the valve plate should be filled up with water or light oil like

kerosene. If after a few minutes no drop in level or leakage is there then

the valve is satisfactory for the use.

16. Pocket has to be cleaned and then put a new gasket.

17. Put the valve in the pocket and turn it by hand then put the cover.

18. Tighten the holding bolt just to touch the valve.

Testing procedure :

Wipe out the valve (both suction and discharge valve) with clean cloth, and check deposits of carbon or sticking of foreign maters. If foreign matter is stuck, disassemble with the valve and carefully clean it with soft cloth

Valve plate

Push the valve plate from the valve seat side using a driver or steel bar and check abnormality of valve plate, face and action of spring. If valve plate is worn, replace it with new one.

Spring

Disassemble the first stage side spring to check its damage or wear. Check the appearance of the second stage side spring if there is no damage or wear. Replace the damage or worn spring with new one.

Leak test

We can do leak test by pouring some water on the valves and we can check for any leakage from the other side by holding.