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LOADING VALVE
DHC TESTERS WITH HV100 LOADING VALVE
If the handle becomes difficult to turn under pressure or will not close, remove the handle
assembly with a 7/8" AF spanner. Check for worn valve spindle and seat, damaged seals or
contamination. Note: If the pressure does not increase progressively when the loading valve is
operated, check if the safety discs have ruptured.
The loading valve (Fig. 3) is fitted with two safety discs which are designed to rupture internally
at approximately 7 bar (100psi) over the maximum pressure. When these discs fail the loading
valve becomes inoperative and the oil flows freely downstream. To replace the discs, remove
the cartridge assembly by unscrewing the 1 3/8" AF hexagon. Unscrew internal holder in
cartridge, remove the two ruptured safety discs and fit new discs, as supplied, one each side
of the spacing ring (Fig. 4). Tighten internal disc holder to 40 lb.ft. (54 Nm). Replace the
cartridge in the valve body. Do not fit discs of unapproved design or material.
REPLACEMENT SAFETY DISCS FOR ALL MODELS
Replacement safety discs available to the following specification: Blue 345 bar, (5000 psi), Red
420 bar (6000 psi). Consult Sales Office for lower pressure ratings. State the Tester model
number when ordering replacements.
Safety Disc Cartridge
Fig. 3
Spacer
Disc
Fig. 4
15
Disc holder
Disc
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