delivery valve and return valve operation

Delivery valve in the raised test sets can be opened a little bigger, so test sets the fastest rise, reducing overhead time trial. When the sample should pay attention to manipulate the Netherlands, according to the sample size must be adjusted for loading speed parher reusable hydraulic hose fittings should not rise too fast, so that the sample is under attack, should not be shut down for no reason, so that the sample suffered a sudden drop in load, thus affecting electronic universal testing machine test data accuracy. If the yield point make the specifications or other special test cases need to repeatedly increase and decrease the load, should also smooth operation.
Parher return valve in the sample, it must be closed, not allowed to have the oil to drain back to the specimen fracture, delivery valve should be closed, and then slowly open the oil return valve, remove the load and make testing machine piston back down to its original position, so that the oil back to the tank, you should note that the delivery valve handwheel Do not overtighten to avoid damage to the tip of the needle oil, oil return valve hand wheel must be tightened, because of the oil has a parher reusable fittings larger needle tip obtuse So easy to damage.