Profile: Walker Co., Inc., W. L. specializes in oil sampling equipment. Our products include biodiesel manufacturing instruments, bombs and bomb baths, bottles, carrying cases, centrifuges, centrifuging tubes & shields, hydrometers, flash point testers, gauging pastes, hydrometers, gauging tapes & thermometers. Our biodiesel manufacturing instrument PHEP plus PH tester is a pocket size tester used for pH detection in the manufacture of biodiesel. The pH range on this simple tester is 0 to 14, and 0 to 50 degrees Celsius operating temperature. The instrument consists of LCD display and cloth junction. It can operate continuously for 750 hours on a single battery. Buffer sachets allow meter to be stored wet for reliable reading, and longer tester life.