Hermetic liquid refrigerant pumps: A solution for eliminating leakage paths paths

A trend in the industrial refrigeration industry is advancing the elimination of leakage paths. For example, the use of welded pipe construction instead of flanged or threaded joints safeguards against refrigerant leakage.

Liquid overfeed systems are known for providing effective heat transfer and reducing operating expenses. In a liquid overfeed system with a mechanical pump recirculating the refrigerant, the use of hermetic pumps is a growing practice.

A pump is used to circulate refrigerant through the evaporator(s) such that the evaporator surface is used more efficiently, providing better heat transfer.

The two types of mechanical pumps used for liquid overfeed systems are either hermetic or open drive. Hermetic refrigerant pumps reduce the risk of unwanted refrigerant leaks because of their seal-less design.

Open-drive vs. hermetic liquid refrigerant pumps

Open-drive pumps depend on mechanical seals to minimize refrigerant leakage from around the shaft. The shaft penetrates into the pressurized containment boundary on the pump.

Shaft seals are usually spring assisted and require lubrication systems to prolong seal life and withstand pumping pressures. Also, open-drive pumps have bearings that must be lubricated. Refrigerant pump seals wear out, costing owners in refrigerant, replacement seals, downtime, and potential fines, injury, and product loss.

Open-drive pumps also use conventional motors, which are subject to dirt, moisture, and ice build-up. Often these motors require auxiliary fan cooling and are noisy.

Hermetic pumps do not require a shaft seal because the shaft and the rotor are one assembly that is completely immersed in the pumped refrigerant. A gasketed, stainless steel can encases this assembly, and is connected to the pump housing.

A hermetic pump uses the pumped refrigerant liquid to provide lubrication to the bearings. Because there are no shaft seals, oil level maintenance is eliminated.

Hermetic motors are totally sealed from external dirt, moisture, and ice. They are cooled by the pumped refrigerant and require no auxiliary devices to provide heat removal. The pump motor provides a secondary containment shell to further protect against refrigerant leakage.

Seal life is three months to several years on an open-type pump. Changing seals requires opening the pump to the atmosphere. Refrigerant leakage indicates a need for maintenance.

With no shaft seals to wear out, costs are minimized in a hermetic pump. Unless a hermetic pump is very dirty, the pump repair interval exceeds five years, at which time bearings may need replacement. Noise or vibration will indicate a need for maintenance.

The solution for an efficient liquid overfeed system with an effective defense against refrigerant leakage can be found in the hermetic liquid refrigerant pump.

Hansen Technologies’ hermetic pumps are compatible with ammonia, R-22, and R-134a, as well as a range of non-corrosive, highly volatile liquids. For more information, contact the company at 6827 High Grove Blvd., Burr Ridge, Ill. 60521; 800-426-7368; 630-325-1572 (fax); info@hantech.com (e-mail); or www.hantech.com (website).

Did you enjoy this article? Click here to subscribe to The NEWS Magazine

You must login or register in order to post a comment.



Image Galleries

2015 ACCA Conference

Images from the 2015 ACCA Conference in Grapevine, Texas. Posted on April 8, 2015.


NEWSMakers: Clint Schreck

Clint Schreck, general manager, Columbus Worthington Air, Columbus, Ohio, discusses winning Angie’s List Super Service Award, how to handle online reviews, and much more.

More Podcasts


NEWS 05-18-15 cover

2015 May 18

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe

Legislation and Regulation

What legislative/regulatory issue is most important to you as a HVAC business owner?
View Results Poll Archive


2015 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research


Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.


Magazine image
Register today for complete access to ACHRNews.com. Get full access to the latest features, Extra Edition, and more.


facebook icontwitter iconyoutube iconLinkedIn i con