N994 Gear Pump & Mtr.

Gear pumps are positive displacement pumps. Each shaft revolution displaces a definite amount of liquid relatively unaffected by the backpressure in the discharge line. Shaft speed and flow are directly proportional. Recommended pressure limits are 100 psi for water and non-lubricants, 150 psi for oil and lubricants. Maximum shaft speed is 1750 rpm. Shaft speed and flow are directly proportional. Motor HP needs to increase with a increase in pump pressure. The nature of a positive displacement pump. See Chart.

A relief valve is necessary in the system if the discharge line contains any throttling devices, such as a shut-off valve, a spray nozzle or other restrictive device. This will return the liquid to the suction side or to the tank. The relief valve is also available as part of the pump itself (R-model pumps). However, built-in relief valves are only good for intermittent service. If used continuously, the pump will over heat. A built-in relief valve is strictly a safety device against overpressure. It will not work successfully as a pressure or flow control device. For this purpose a separate relief valve in the pressure line must be used.

Service life will be increase substantially if the liquid pumped is clean and has a lubricity value. These pumps have extremely close tolerances.