Pressure gauges are instruments used to measure the pressure of a gas or liquid inside a vessel and, often, to help ensure the optimal amount of pressure for a given application. Pressure gauges can range from everyday instruments, such as those used to measure the air pressure in a car or bicycle tire, to highly accurate gauges used in mechanical and industrial processing. Most often, pressure gauges measure pressure relative to a reference measurement. Gauge pressure measures the pressure of something relative to ambient air. For example, a tire pressure gauge or a blood pressure gauge measures the air in a tire or blood flowing through veins relative to ambient air. Differential pressure is the difference in pressure between two points, such as when measuring liquid flow along various points in a pipeline. An absolute pressure gauge measures pressure relative to a perfect vacuum, for example, an atmospheric or barometric pressure gauge. All types of pressure gauges include either a male or a female mount to connect to the vessel where pressure is being measured, and they display results on a dial with varying increments of measure across a given range.
Precision Instrument Company, a division of Engineered Specialty Products (ESP), manufactures measuring instruments including pressure gauges, needle valves, thermometers, and plumbing and HVAC gauges. The company, founded in 1983, is headquartered in Kennesaw, GA.