155 Commerce Blvd.
Loveland, OH 45140

800.860.2983

Local: 513.583.4900
Fax: 513.583.4819
Email: info@periflo.com

Roller vs. Shoe Technology

Shoe Technology

Shoe compressor technology consists of a fixed shoe that slides over the surface of the hose during compression and main rotor bearings that are isolated from the pump housing by a single lip seal. This design is suitable for higher operating pressures up to 220 psi, however this sliding shoe action creates frictional heat, requires additional force, higher torque, larger drives (vs roller designs), and imparts higher linear stress on the hose. The heat of friction is dealt with by running the hose in an immersion bath of heat transfer fluid (hoselube) that serves to conduct the heat away from the hose, and provide modest lubrication.
The hoselube is contaminated whenever there is a hose failure and must be replaced. The glycerin level must also be maintained during operation of the pump or overheating and rapid hose failure will result. The high starting and running torque limits low speed operation to about 4 rpm.

Hose leak detection is handled by installing a float type level switch at the mid-point of the pump body. As the leaking media dilutes the hoselube the level rises and activating the switch. This is used to turn off the pump. This also means that the contaminated liquid has filled at least 50% of the pump housing and the lip seal is the only thing protecting the rotor bearings from the media.

Shoe compressor technology is used in PeriFlo RBT series pumps, all Watson Marlow® SP and SPX series pumps, and most other competitors.

Roller Technology

This technology uses rollers mounted on permanently lubricated greased bearings to roll smoothly along the surface of the hose during compression and main rotor bearings that are isolated from the pump housing by a single lip seal. This design is suitable for operating pressures up to 115 psi. The hose and outer roller surfaces are permanently lubricated with a food grade silicone grease. The result is lower starting torque, lower operating torque (vs shoe designs) and lower mechanical stress on the hose. This typically results in a smaller drive, smoother operation and longer hose life (up to 20%). The smooth operating torque allows pump operation over a very wide turndown range and at very low speeds, to a fraction of an rpm. This greatly enhances the flexibility of PeriFlo pumps and opens up many new applications to the many benefits of peristaltic technology.

Hose leak detection is handled by installing a capacitance probe (switch) in the bottom drain port of the pump where it provides very early detection of the presence of any aqueous material. This allows the shutoff of the pump and alarm with only a few ounces of leaked material. As the first few ounces of pumped media leak into the pump housing, the switch is activated, allowing shutoff of the pump and alarm indication with a minimal amount of leaked material in the housing. The main rotor bearings, protected by a lip seal, are never threatened. The leak is detected so early that the roller bearings, also protected by lip seals, are not threatened.

Roller compressor technology is offered by PeriFlo in our FMP, AMP and ChemTUFF series pumps.

Summary

• Roller technology offers lower hose stresses and longer hose life – up to 20%
• Roller technology allows early leak detection, less leakage and better containment of the pumps media – and reduced risk of main rotor bearing contamination.
• Roller technology allows lower operating speeds and wider turndown ranges, excellent for metering
• Roller technology requires smaller drives (motors and VFD’s)
• Roller technology is limited to 115 psi operating pressures. Shoe technology is suitable for operating pressures to 220 psi

In addition, PeriFlo’s FMP series roller design pumps typically have a slightly higher displacement per revolution than the equivalent physical sized shoe pump. This also allows for lower speed operation which also serves to improve hose-life.

®Watson Marlow is a registered trademark