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GAS CHARGE
NITROGEN GAS PRESSURE
The nitrogen gas pressure must be measured with no preload on the tool. Remove the
tool; or position the hammer with the tool fully extended against the tool retaining pin.
The hammer must not be resting vertical on the tool. The gas pressure in the hammer
will vary according to the gas temperature.
PREFERRED METHOD
The preferred method to measure or charge the nitrogen gas pressure is with the
hydraulic system temperature stabilized at maximum operating temperature. The chart
showing values for “Operating Temperature” should be used, see below.
ALTERNATE METHOD
The nitrogen gas pressure can be measured or charged at ambient temperature (cold),
before operating the hammer. See the chart “Ambient Temperature” below.
DO NOT OVERCHARGE THE HAMMER!
Exceeding the gas pre-charge specifications can result in damaging hammer
components. The NPK WARRANTY does not cover failures resulting from exceeding
the specified nitrogen gas pressure.
NITROGEN GAS PRE-CHARGE
HAMMER
MODEL
AT AMBIENT TEMPERATURE
(cold, before operating)
*psi (bar)
AT OPERATING TEMPERATURE
(hot, after 1 to 2 hrs. operation)
*psi (bar)
PH1 175 (12) 220 (15)
PH2 175 (12) 220 (15)
PH3 175 (12) 220 (15)
PH4 175 (12) 220 (15)
*The gas charge tolerance is plus 0, minus 25 psi (2 bar).
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