Peristaltic pumps are a type of positive displacement pump used for pumping a variety of fluids, particularly when it is important that such fluids don’t come in contact with internal pump components. The fluid is contained within a flexible tube fitted inside a circular pump housing. A rotor with a number of rollers compresses the flexible tube. As the rotor turns, the part of the tube under compression is pinched closed thus forcing the fluid to move through the tube.
Peristaltic pumps are often used to pump sterile or aggressive fluids without exposing those fluids to contamination from exposed pump components. Various applications include dialysis machines, carbon monoxide monitors, beverage dispensing, paint mixing, concrete pumping and pharmaceutical production. They are particularly well suited for pumping aggressive chemicals, high solids slurries and other materials where isolation of the product from the environment, and the environment from the product, are critical.
Problems with Conventional Drives
Peristaltic pumps require relatively high torque at low rotational speeds, typically in the range of 5 to 500 RPM, well below the direct drive capability for conventional AC or DC motors. As a result, conventional motors are operated at a higher speed (over 1000 rpm) and a speed reduction gearbox is necessary to achieve the required torque and rotational speed. These geared drive systems are large, heavy, inefficient and the gearbox increases cost while causing a reliability and maintenance burden.
Compared to conventional geared systems, ETM Direct Drive motors deliver high continuous torque at low rotational speeds, which eliminates the need for a speed reduction gearbox. This greatly reduces the drive system weight, size,
temperature, and power consumption of the pump system. In addition, the user benefits from a wider operating speed range as a result of the ETM motor’s wider turndown ratio. ETM drive systems are panel mountable, come pre-wired with 110V plug, and include advanced control features such as a touchpad user interface. ETM motor sizes cover a range of both peristaltic and hose pumps. An ETM Direct Drive motor attached to a leading manufacturer’s peristaltic pump head is shown in the image below. The drive system consists of an M100 Direct Drive Motor and Controller with user interface. The image below shows ETM’s M100 Drive Drive motor and controller with peristaltic pump.
ETM Direct Drive Advantages
ETM’s motors are specifically designed for high continuous torque at low rotational speeds and use proven transverse flux technology with increased pole count and low resistance coils delivering 5-10X more continuous torque by mass compared to conventional AC or DC motors. Conventional drive systems have more moving parts and weigh up to 5 times more than an ETM Direct Drive. In addition, the higher losses in geared drive systems mean the motors need to be oversized to meet the output power requirements. As a result, the ETM drive system has been proven to be as much as 50% less expensive than competitive geared drive systems.
Weight and Size Reduction
In one example shown in the image below, a leading peristaltic pump manufacturer replaced a 45lb (20kg) AC induction motor, gearbox, and controller with a 10lb (4.5kg) ETM Direct Drive system resulting in a 78% weight reduction. The ETM Direct Drive is also much more compact, occupying less than half the volume than the AC geared system. This enables greater portability and more flexible packaging for the system integrator.
The weight and size of AC geared systems requires “foot mounting” to the floor or horizontal structure, while ETM’s motor enables “panel mounting” where the pumphead is on the front side of the panel with the motor on the back. The image below shows a panel mounted ETM M100 Motor.
Efficiency legislation is creating an ever-growing focus on motor and pump system efficiency. OEM’s are increasingly challenged to meet new and anticipated efficiency regulations while offering their customers a cost effective product. AC induction motors suffer from high losses in variable speed/load applications. As induction motor speed moves away from nominal RPM, efficiency can fall to less than 50%. Gear losses, caused by sliding friction and movement of viscous oil, further compound overall drive system power loss. ETM Direct Drive motors have very low coil resistance and high pole count, an ideal combination for efficient torque production at low speeds. The image below shows an example where input power consumption is measured at several points across the speed and pressure operating range for a .5HP (370Watt) peristaltic pump. Compared to the AC geared system, power consumption is reduced 29-54% for the ETM direct drive system.
Increased Operating Range
Most AC geared peristaltic pump drive systems offer a maximum turndown ratio of 10:1. This means the maximum pump speed is 10 times greater than the minimum speed. This ratio is often limited by variable frequency drives used to operate AC induction motors. ETM Direct Drive systems include a controller with a speed range from 5 to 500RPM, a turndown ratio of 100:1. Testing has also shown that ETM Direct Drive systems are capable of operating at higher continuous loads compared to much larger, heavier AC geared systems. Refer to the image below.
Improved Reliability and Maintenance
Gearboxes used in conventional drives are often the weak link in pump systems. Over time, gearbox seals leak, gears wear out, and the systems require increased maintenance. ETM Direct Drive Systems have a single moving part, the motor rotor, which enables greater reliability, reduced maintenance and reduced noise. ETM Direct Drive Motors have been proven in several markets. Beginning in 2011, tens of thousands of ETM motors sold to demanding industrial customers have accumulated millions of operating hours in the field.
Simpler Inventory Control and Less Cost
Because ETM pump motor drive systems have a wider load/speed operating range, OEMs can replace a number of motor and gearboxes with far fewer ETM Direct Drive systems. This enables much simpler inventory management, improved working capital turns, easier replacement parts service, and lower inventory costs.
Ease of Installation and Use
Installation of AC gearmotor systems often requires an electrician to connect the controller to building mains while ETM Direct Drive systems come pre-wired with a 110V cable and plug. Simply plug into your building’s 110V power and you’re ready to use the motor. 220V systems are available as well.
ETM Direct Drive systems also offer a digital and analog interface including start/stop, analog speed input/output, user configurable speed pre-sets and multiple auxiliary inputs/outputs for user configured sensors. ETM systems can also be controlled via Modbus (RS-485). A touchpad HMI with LCD display is standard on ETM controllers.
ETM Direct Drive motors are available with rated torque from 60 to 350In-lb (7 to 40N-m) covering a wide range of peristaltic and hose pump sizes.
ETM’s Direct Drive enables us to offer our customers a cost-effective pump system that’s significantly smaller and lighter than anything we’ve seen on the market.
Noted the sales leader for a major peristaltic pump manufacturer
ETM’s motor and drive systems are commonly used for conveyors, doors, pumps, fans, packaging equipment and other applications. These compact and lightweight M-series motors and controllers are available with adjustable speed ranges from 0 to 1800 RPM, output torques from 40 to 1800 lb. in. and 0.71 to 2.2 HP ratings. They are UL Listed and RoHS Compliant.
For more information, contact: Electric Torque Machines, 1409 East Butler Avenue, Flagstaff, Arizona 86001. Phone: (928) 779-3169, Email: firstname.lastname@example.org,
Electric Torque Machines (ETM) motor and drive technology is the result of nearly 10 years of product development, testing and scaling of high volume manufacturing. Our patented technology is a major advancement in electric motor development providing low cost, high efficiency, high continuous torque density, high reliability and a wide operating window to reduce costs.