OTC 4235 50 GPM Hydraulic Circuit Tester Hydraulic oil flow testers accurately measure oil flow temperature and pressures against manufacturers' specifications Troubleshoot hydraulic circuits and isolate faulty components on open or closed hydraulic systems Automatic pressure compensating load valve that lets you increase flow without affecting the pressure settings Temperature flow and RPM readings are displayed in metric or English and accurate to within plus or minus 2 percent of full scale Tester is protected by a safety disc which ruptures automatically if pressures exceed the upper limits