Helical External Gear Pumps

How does a Helical External Gear Pump work?

The pump features a horizontal shaft, 180° port position and has 2 external helical gears.

The pump shaft operates, moving the gears which draws liquid into the port. The liquid fills the space between the gears and moves towards the outlet of the pump as the shafts turn.

By-Pass/Pressure Relief Valve Operation:

The intended purpose of a By-Pass or Pressure Relief Valve (PRV) is to ensure that the pump and drive unit are protected from unnecessary damage that may be incurred during over-pressurisation which is mainly caused by closed valve operation or blockages in the discharge line. By-Passes can be either installed on the pipework and route fluid back to the suction of the pump or tank, in the form of a By-Pass Circuit, or indeed installed directly on the pump head, as detailed below.

The By-Pass, when opened, relieves excess fluid and pressure from the discharge section of the pump to the suction side and effectively allow the pump to recirculate within itself until the blockage in the line has been cleared or closed valve opened to allow the process medium to carry on through the system and drop the pressure in the line to an acceptable level for the installed equipment.

As By-Passes are spring-loaded and adjustable, they can be tweaked in situ to cater for changing system or pump requirements.

The Helical Gear Pump Range has a compact robust design with many beneficial features including:

• Shaft support on both sides of the gears
• Pressures up to 300 meters
• Wide speed range, up to 50-1500 rpm
• Often used as lubrication pumps in machine tools, in fluid power transfer units, and as oil pumps in engines.
• Precise transfer and metering applications involving polymers, fuels, and chemical additives.
• Can be fitted with Heating Jackets to maintain fluid temperature
• By-Pass/Pressure Relief Valve can be installed to protect the pump from over-pressurisation

Max Capacity (m³/hr)	250m³/hr
Max Pressure (m)	150m
Viscosity (cSt)	up to 55,000 cSt
Max Speed (rpm)	1500 rpm
Max Temperature (°C)	350°C
Materials & Limits
Connection Sizes	2” – 10”
Capacity Range	1 – 320 m³/hr
Pressure Range	10 – 150m
Temperature Range	up to 350ºC
Speed Range	50 – 1500 rpm
Viscosity Range	20 – 55,000 cSt
Pump Body & Cover	Cast Iron, Ductile Cast Iron, Cast Steel, Stainless Steel AISI 304/316
Gears	Cast Iron, Ductile Cast Iron, Cast Steel, Stainless Steel AISI 304/316
Bearings	SnBz12 Bronze, Carbon Graphite, Ina Bushing Bearings
Sealing	Soft Seal / Packed Gland, Mechanical Seal

Sizes Available: