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Mini Bellows Metering Pumps

Mini Bellows Metering Pumps are ideal for low flow, low pressure metering applications. The pump is constructed entirely of plastic and uses GRI’s time-proven bellows technology to provide an accurate chemically-resistant metering pump with a long life, at an economical price.

Mini Bellows Metering Pump Operation:
The Mini Bellows Metering Pumps operate on a positive displacement principle. The rotation of the motor shaft is transmitted into an up and down linear motion through an adjustable concentric crank mechanism. This motion provides a continuous compressing and relaxing force on the bellows module, forcing fluid between two check valves located in the module’s valve body. Up to two separate bellows modules can be operated by single motor for proportioning up to four separate fluid mediums. The flow rate of each module is independently adjustable. Multiple bellows modules operate out-of-phase with each other for most efficient power usage.

Optimum Operating Conditions:
Optimum operating conditions consist of a 6” minimum suction life and a discharge head of not less than 6”. Pumps must be mounted vertically with the valve body at the top to obtain maximum metering accuracy. For conditions where a positive suction head condition exists, an anti-siphon spring or anti-siphon spring kit can be added to aid the poppet valve seal properly during operation. See Accessories PDF file located in the Product Resources section located above right.

Bellow Metering Pump Flow Rates:
The flow rate of each bellows module is regulated by three factors:

1. Diameter of the bellows,
2. Speed of the gearmotor,
3. Adjustment of the module stroke length.

The full stroke displacement and discharge pressure of the pump is dependent on the size of the bellows as shown below. If higher discharge pressure pressure is required, please consult factory for an OEM solution.

Bellow Metering Pump Flow Adjustment:
The ½” and ¾” bellows modules can be adjusted to 20% of maximum stroke length, while 1”, 1-1/2” and 2” bellows modules can be adjusted down to 10% of maximum stroke.

Note: Best priming and metering accuracy occurs when the stroke length is 50% or greater.

Standard Crank — Adjustment cannot be made while pump is operating. An adjusting screw changes the stroke length of an eccentric crank.

Mini Bellows Metering Pump Specifications:
Average Repeatability — From stroke-to-stroke ± 0.75%
Flow Rates — Range to 270 ml/min, Tandem models range to 432 ml/min
Max Fluid Temperatures — To 140°F (60°C)
Max Discharge Pressure — To 6 psi

Note: Reduce pressure rating by 50% for fluid temperatures over 120°F (49°C).

Viscosity/Slurries — Maximum fluid viscosity is 5,000 centistokes. Poppet valves can handle fine slurries. Duckbill valves are recommended for heavy slurries or fibrous materials. Heavy slurries should be flushed from the pump before shutdown.

Note: All testing is done with water at an ambient temperature of 80 degree F. If specific gravity or viscosity of fluid being pumped is significantly greater than water (1.0), please consult factory.

Gearmotors:
The standard motor available for the Mini Bellows Pump is an AC voltage synchronous motor. Motors are UL recognized and continuous duty rated and are available in 115V, 50/60 Hz or 230V, 50/60 Hz.

Materials in Contact with Solution:
Connectors — Polypropylene
O-Rings (Elastomers) — EPT/EPDM or Viton®/Fluoroelastomer
Poppet/Duckbill Valves — EPT/EPDM or Viton®/Fluoroelastomer
Bellows — Standard Polypropylene Materials
Additional materials available, refer to OEM Section for details.

Mini Bellows Metering Pump Selection:
The pump selection procedure is detailed in the Mini Bellows Metering Pump Selection Guide or the Tandem Mini Bellows Pumps Selection Guide link or by navigating to any of the MBMP Series pumps listed below.

Features
•	Average repeatability from stroke-to-stroke, ±0.75%	•	Dry run capability
•	Self-priming	•	No dynamic seals
•	Superior corrosion resistance	•	Economical
•	Simple flow adjustment

Exploded View

Performance by Product Series
Single Pump Mini Bellows Click above image or series link to customize a single bellow pump configuration. Service Data Sheet
Tandem Mini Bellows Click above image or series link to customize a 2-tandem bellows pump configuration. Service Data Sheet

OEM Options

Motors

Speeds Standard synchronous motor speeds are 8, 12, 15 and 24 RPM at 60 Hz. Shaded pole motor speeds can be supplied in virtually any speed up to a maximum of 90 RPM. Voltages Standard voltages are 115V, 50/60 Hz or 230V, 50/60 Hz. However, the following special voltages are also available: 12 and 24VDC. Designs The standard motor is an AC voltage synchronous motor. Depending on the type of mini bellows metering pump, the following motor types are available: shaded pole, stepper and DC.

Poppet Valves and O-Rings

The standard elastomers for the poppet valves and O-rings are EPT/EPDM and Viton®/Fluoroelastomer. These elastomers have historically been able to handle the vast majority of the applications in which we’ve been involved. However, Butyl, Hydrin, Kel-F®, Silicone and Nitrile can be supplied for chemicals requiring such materials.

Duckbill Valves and O-Rings

Duckbill valves are required in those applications where heavy slurries or fibrous materials are being pumped. Heavy slurries should be flushed from the bellows before pump is shut down. Duckbill valves are available in the same elastomers as the poppet valves.