Advertisement
LOADING VALVE
DHT 751 & 751 HP TESTERS
If the loading valve becomes difficult to turn under pressure or will not close, remove the 4 bolts.
Check for worn valve seat, damaged or leaking seals and contamination. Note: If the pressure
does not increase progressively when the loading valve is operated, check if the safety discs
have been ruptured. Assemble the loading valve into the flow block ensuring that the guide pin
is located in the slot on the poppet valve (Fig. 7).
Fig 7
SAFETY DISCS
DHC 751 & DHC 751 HP
The loading valve is fitted with two safety discs which are designed to rupture internally at
approximately 100 psi (7 bar) over the maximum pressure. When the discs fail, the loading
valve becomes inoperative and the oil flows freely downstream.
To replace the safety discs remove the loading valve assembly from the flow block. Unscrew
the safety disc holder from the valve by carefully gripping the valve on the 35mm diameter.
Remove the disc spacer and the ruptured discs from the valve and disc holder. Carefully
preform the two discs by pressing them by hand between the disc holder and spacer then place
one new disc inside the valve and replace the spacer. Place a second disc on top of the space
and screw in the disc holder (Fig. 8). Tighten the holder to 40lb. ft. (54 Nm)
Grip on this Diameter
Disc holder
Disc
Spacer
Disc
Fig 8
17
Advertisement
