Efficient Pumping

Develop a partnership before purchasing a pump.

In today’s gases market, everyone from the largest multi-national to the smallest distributor is keenly aware of how competitive the environment has become. Large organizations are addressing the situation in part by refocusing their business, buying or selling activities in line with their chosen strategy for profitability. Smaller operators might not have such grand options available to them, but they do share some objectives with the larger organizations, such as cost reduction and the pursuit of profitable sales.

In the area of cost reduction, some opportunities can be overlooked in the midst of the day-to-day pressures of running the business. One of them, cryogenic pumps, will be discussed in this article.

The cryogenic pump is the heart of most cylinder filling and transport operations, providing the necessary power to transfer liquid into and out of vessels during bulk liquid delivery and moving that liquid through vaporizers to fill cylinders for sale and distribution.

Various pump solutions are available that can help in the effort to reduce operating costs. Of course, purchase price can always be negotiated, and the buyer can shop around for a cheap pump. To achieve long term profitability for his or her company, the buyer should ensure that the pump also gives reliable service and has a low maintenance cost. This is the lifetime cost of the unit.

Composite Seals
Examples of available technology to reduce lifetime cost include the modern composite seals for centrifugal pumps. The mechanical seal is generally the weakest component in a centrifugal pump and eventually it will wear out, indicated by a cold gas leak or liquid leak in the seal area.

Composite seals employ a composite material for the sealing face in place of the traditional carbon face. As compared to carbon, the composite material is less brittle and reacts better to low temperatures and moisture. It is also much more tolerant of dry running, such as can occur during pump start-up.

How many organizations can quantify all the costs associated with switching out a pump for maintenance? These costs include labor, lost productivity, failed delivery, fuel costs to return the vehicle to the maintenance shop, etc. Certainly these hidden aspects add significantly to the overall cost and, in some cases, may be equal to or greater than the bill for the pump repair itself.

To help with the hurdle of finding the cash to fund a new pump purchase, pump manufacturers now offer leasing programs, some of which include a maintenance program within the lease price. This allows the purchaser to easily bud-get and spread the cost over the lifetime of the pump.

Installation
A very important aspect with piston pumps is the design of the installation. Suction and gas return (vent to tank) lines should be as short as possible and have a constant slope between the pump and tank connections. High points, long lines and sharp changes of direction all affect the net positive suction head (NPSH) available to the pump. The pump is more likely to be starved of liquid and cavitate before the tank level gets near to empty. The result is more frequent liquid deliveries due to lost capacity on the tank and increased maintenance costs on the pump. Though it depends on duty cycle, operating pressure and other aspects, a good installation should allow a piston pump to operate for at least 12 months or 1,000 running hours between maintenance.

How do you know that you may have an NPSH problem? One easy question to ask is: Does my pump stop building pressure, change sound (from a solid “knock” to a quieter noise), or display similar problems when the tank is more than one-third full? With a good, efficient installation, most pumps should be able to run the tank down to one-third or one-fourth full without too much of a problem.

Correct installation advice should be part of the service offered by the pump supplier to the installer, and most reputable manufacturers offer this advice free of charge.

The purchase of a pump system should be seen as a partnership between the purchaser and the pump manufacturer. After all, the manufacturer should want the customer to be happy with the purchase. The customer is likely to be working with the manufacturer over a number of years, as he or she seeks to operate and maintain the pump efficiently and at lowest possible cost.

Gases and Welding Distributors Association
 Mark Sutton Meet the Author
Mark Sutton is business manager at Cryostar USA in Santa Fe Springs, California, and on the Web at www.cryostar.com.