Gorman Rupp Industries  - Bellows Metering  Pumps

Designed to accurately meter (to ± .5% from stroke-to-stroke) a variety of liquids including corrosive chemicals, detergents, soft drink syrups and photographic solutions.

Bellows metering pumps operate on a positive displacement principle. Pumps are designed to displace both corrosive and non-corrosive fluids. Accurate to ± 0.5% from stroke to stroke, when pump is set 50% to 100% of full stroke. Discharge pressure is maintained over the entire flow range of the pump. Poppet valves are utilized to prevent backflow; and springs are available to provide a positive shutoff, preventing siphoning through the pump in applications where a positive suction head exists.

Materials in Contact with Solution
Tubing connectors - Polypropylene
O-Rings and Valves - EPT, Hypalon®, or Viton®/Fluoroelastomer
Bellows - Three different Polypropylene formulas

OEM Options
Modifications for OEM quantity applications include different materials of construction, body and motor styles and different capacities.

Operating Principle:

The bellows pump operates on the positive displacement principle. The rotation of the motor causes a crank mechanism to turn. This motion of the crank mechanism causes the bellows to compress for one half of the motor rotation, causing the pump to dispense liquid into the discharge line. During the other half of the motor rotation, the motion of the crank mechanism causes the bellows to expand, drawing liquid from the suction line into the bellows module. The pump uses two valves to control the flow of the liquid through the pump. Discharge pressure is maintained over the entire flow range of the pump.  Pictured to the right is a dual head unit - four head maximum.  GRI-Standard Bellows

Standard Bellows Pumps - flows to 2100 ml/min - pressure to 50 PSI

Compact Bellows Pumps - flows to 1600 ml/min - pressure to 5 PSI

Mini Bellows - flows to 270 ml/min - pressure to 15 PSI

Single Stroke - for a single chemical shot - 2.5 to 55mL

Frequently Asked Questions

PDF Bulletins

Standard Bellows Metering Pumps 

 Standard Pumps are available in six bellows diameters: 1/2", 3/4", 1", 1-1/2", 2" and 2-1/2". Flow rates range from 3.9 to 3000 ml/min. Two crank mechanisms (standard and BEL O JUST®) allow easy adjustment of the stroke length. The BEL O JUST® crank can be adjusted while the pump is operating. This unit is available with a heavy duty motor and a Dial-A-Flow motor speed control.  See below. GRI-Standard Bellows

Compact models were designed for applications with low pressure requirements. Maximum discharge pressure to 5 PSI. Pumps with up to 4 bellows modules are available. Flow rate of each bellows module is independently adjustable.  Pumps are only available with the standard crank mechanism. 

Pumps are available in five bellows diameters: 1/2", 3/4", 1", 1-1/2" and 2". Flow rates range from 4.5 to 1620 ml/min. and are easily adjusted.  Accurate to ± .75% from stroke-to-stroke.  Compact Bellows Overview

Mini bellows models are ideal for low flow, low pressure metering applications. The pump is constructed entirely of plastic and utilizes GRI's time-proven bellows technology to provide an accurate chemically-resistant metering pump with a long life, at an economical price.  Pumps are available in four bellows diameters: 3/4", 1", 1-1/2" and 2". Flow rates range from 1.8 ml/min. to 270 ml/min. and are easily adjusted.  Mini-Bellows-Overview

Flow rate for tandem pumps is limited to 432 ml/min.

Single Stroke Bellows Pump

This pump is used to produce single stroke of chemical.  Flow ranges of 2.5 to 55 mL.

 Details PDF file GRI-Single Stroke

Frequently Asked Questions

What factors determine the flow rate of the pump?

There are three factors that determine the flow rate from a bellows pump. The bellows size affects the maximum amount of fluid dispensed per stroke of the pump. A second factor is the rotational speed of the motor. Speeding up the motor creates greater strokes in a given time period; therefore, increasing flow rates. Finally, the flow rate of all bellows pumps can be adjusted by modifying the length of the discharge stroke.

Can bellows pumps be run dry?

Yes, however, running the pump dry can cause liquid left in the pump to dry and cause possible valve malfunction.

Is there an optimal stroke length for the pump?

It is best to run the pump as close to 100% of stroke length as possible. Running the pump at less than 50% can have an adverse affect on the accuracy of the flow.

Can I buy pumps and parts from KTH Sales - 

Yes, please provide details for the chemicals for new applications.  Complete model numbers with voltage and tube fitting options is required for replacements.  Minimum order is $ 50.00.

Do you repair pumps?

Yes, repairs require authorization to be received by our shipping departments.  Contact customer service by e-mail or phone 219-736-0060.  

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