| Dwyer® solid plastic stationary gages — or draft gages — are offered in inclined and vertical (well-type) styles for highly accurate laboratory or general industrial service, for measurement of low range gas and air pressures, positive, negative or differential. To assure the accuracy required in instruments of this type, all machining of bores and wells is to the highest standards of precision backed by Dwyer’s years of experience in the fabrication of acrylic instruments. Over-Pressure Safety Traps Prevent Fluid Loss Exclusive Dwyer® over pressure safety traps assure that over range pressures whether gradual or a sudden surge will not force the liquid out of the gage. Over pressures simply float the cork, force the O-ring over the opening and seal the fluid in the gage. When pressure is reduced, cork drops down releasing the O-ring safety trap opens and the gage continues in operation | 
