Catalogues - milton-roy-metering-pump-technology-b210

Catalogue Milton Roy Metering Pump Technology B210

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Milton Roy Flow Control Division - 3702, 2977, 3534, 208163, 3532

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CENTRAC — The Automatic Process

Advanced Drive Technology

rue innov

ntrac represents a new result is a metering pump that boasts

Centrac is different from traditional designs in many ways. The most significant way is the close relationship between the driver and drive mechanism and how they enhance overall pump performance. To understand Centrac better, these two design elements and their interdependence need to be explored.

twice the accuracy over a turndown ratio ten times greater than traditional designs.

Centrac's name clearly announces its capabilities:

CENT-100:1 turndown ratio

R-Response & Reliability

AC - + 0.5% steady state accuracy

oncept in metering pump rive design. It is the first

true innovation in metering pump drives to be introduced in decades.

Centrac was developed by combining the highest level of gear reduction design, and the latest technology in electronic variable speed drives. The

Centrac's Unique Gear Reduction System

Centrac's impressive operating characteristics are the result of a unique constant stroke length drive mechanism that depends on a special electronic variable speed drive to vary pump flow rate. This offers a number of advantages.

Traditional designs utilize worm gear sets to convert motor rotation to reciprocating motion through an eccentric or similar mechanism. Worm gears are the best choice when the drive mechanism is required to incorpo

reciprocating motion, this gear set runs quietly and efficiently with few moving parts. All moving parts are submerged in oil to ensure long life.

The graph below indicates the greatest advantage of Centrac's special gear design. The flat torque curve (vs. the worm gear set) allows Centrac to operate at or below 1% of speed without placing extra demand on the motor, thus permitting Centrac's 100:1 turndown ratio. The simple drive mechanism also allows Centrac to be easily duplexed within

Operator Control Station

Centrac's Advanced Electronic Variable

Speed

Drive

Conventional AC and DC variable speed drives are limited to turndown ratios between 5:1 and 30:1. This is insufficient to take advantage of the turndown capabilities of Centrac's gear design.

New technology in brushless dc motors and controllers has created advanced drives capable of strong operation at low speeds. Centrac's variable speed drive delivers rated torque at less than 1% (100:1 turndown) of maximum rated RPM while maintaining steady state speed control at better than + 0.1%. It is the

Motor Drive Gear{ (18 to 1800 RPM/

rate a vari-

Low Speed Eccentric & Gear

the same housing

by adding a second piston and liquid end opposite the primary liquid end. Centrac's capacity can therefore be doubled economically and efficiently.

able stroke length adjustment. They operate well at high rotary

Piston

speeds, due to an oil shield that develops

Block transfers Rotating Eccentric Motion to Reciprocating Motion CENTRAC Scotch Yoke Drive

between

the gear surfaces. Unfortunately, they lose that shield at lower speeds, which causes wear and raises motor torque requirements. This limits worm gears to a 10:1 turndown ratio.

Centrac, on the other hand, utilizes a special helical gear set. Since there is no need for stroke length adjustment, the gear set is very simple. Also, helical gears are known for operating with low noise and low friction. Combined with a basic scotch yoke mechanism to develop

100:1 Turndown 10:1 Turndown

180

160

140

120

^ 100% '

Typical of CENTRAC

Full

0 10 20

100 1 75 2 00 Motor Speed-RPM

1700

1800

perfect match

Load

for Centrac's drive mecha

Torque vs. Motor Speed-CENTRAC and Worm Gears

nism.