The following article originally appeared in the February 2006 issue of Pumps & Systems Magazine:
Take a
Load Off
By Michael Callinan, Emotron Inc.
This plant had three particular pumps that averaged greater than $90,000 per year in maintenance costs and downtime. After installing these power monitors, maintenance and downtime costs for the next two years vanished. Thats right . . . zero.
International Specialty Products (ISP) Chemicals Inc. serves the pharmaceutical, beverage and personal care industries as the single largest privately-owned specialty chemicals producer in the U.S.
The ISP Calvert City, KY facility, built in 1956, is the largest of the company's seven American manufacturing plants, with over 500 employees producing 325 chemicals.
This plant usesmany chemicals as feed materials, including acetylene, ammonia, benzene, acetone, ethanol, butanediol, vinyl acetate, isopropyl alcohol, iodine, styrene, methanol, propane, cyclohexylamine, ethylamine, cyclohexane, ethyl acetate, isobutylene, and isopropyl acetate.
ISP Calvert City manufactures a variety of products, including Butyrolactone, 2-pyrrolidone, Vinyl Pyrrolidone, Poly-Vinyl Pyrrolidone, Gantrez, Vinyl Ethers, Stabileze, ACO-5013, various pharmaceutical intermediates and personal care intermediates.
Being sensitive to productivity losses caused by process or operator glitches, the plant has tried a number of monitoring technologies to prevent downtime in its pumping systems.
According to senior reliability engineer Ken Myers, "Several technologies were employed in an effort to reduce downtime issues resulting from a failure in the process equipment. Temperature sensors were installed at the bearings and in the casing of the magnetic drive pumps. Flow switches were installed in an effort to capture dry run or no flow conditions. Both devices proved unreliable in preventing consistent premature failure due to the lack or response under low load conditions."
Layout of the power monitors inside the control panel.
Another technology sometimes used in an attempt to protect pumps from run dry conditions is "current monitoring." Unfortunately, this solution is defeated by the reality of science - current monitoring rarely works in detecting underload conditions on AC induction motors.
Motor current (amps) changes very little until the motor's load reaches or exceeds 65 to 70 percent of its rated power. Even after this point, it is non-linear.
This phenomenon makes it extremely difficult to establish protection for the pumps. What was originally intended as a simple inexpensive solution now becomes an operator nightmare, as costs of nuisance trips (process downtime) far outweigh the perceived savings.
In 2000, ISP was introduced to the Emotron M20 motor shaft power monitor by their local pump supplier, BRI Inc.
"Our initial main goal was to protect our magnetic drive pumps from dry run conditions that proved detrimental to the operation of the pump," says Myers. "Prior to installing these power monitors, we had three particular pumps involved in significant maintenance issues that averaged greater than $90,000 per year in maintenance costs and downtime. After the power monitors were installed, average maintenance and downtime costs for the next two years dropped to zero."
Pump load changes that occur due to run-dry or other abnormal conditions produce corresponding changes in the load of the motor. The power monitor uses a unique AutoSet feature that allows four protection set points to be established in just three seconds with the push of a single button. As a result, the power monitoring of motor shaft power (BHP) provides reliable pump supervision and has a direct correlation to the pump curve.
The ISP Calvert City maintenance team includes instrument/electrical planner Paul Moss
(on left) and reliability engineers Kenny Myers (center) and Ryan Brown.
Myers adds, "Some other equipment problems we encountered came to our attention, such as overload protection, underload situations, troubleshooting, efficiency verification, and failure mode identification. These other problems led us to install the power monitors on other varied applications, such as positive displacement pumps, transfer elevators and conveyors, and product blenders.
When assessing reliability solutions, ISP looks for a rapid return on investment. "We saw an immediate ROI with this power monitor," states Myers. "The cost of installing each unit, including the purchase price, was approximately $1,000. From our experience, we expect to see a ROI as quickly as one week in most cases."
The plant has actively continued to pursue new applications for the power monitor on its process pumps, with regard to monitoring reliability, range of capacity, ease of installation in MCC buckets, and user friendly set-up.