subject: Diamond Shaft Seal for the refrigeration compressor industry [print this page] The refrigeration compressor industry is a complex industry. It is a technical system that combines the components of refrigeration, electricity and mechanical parts all into one, with the chemical reaction between the refrigerant and lubrication oil often occurring at high temperatures. The refrigeration process brings further complications and challenges because the refrigerant (ammonia) changes from liquid into gas and back into a liquid. Martin Wierbosch, the owner of RM Support and an expert in the field of refrigeration compressor systems, takes us through some of the challenges that shaft seals encounter and introduces us to one of his new products, Coldores.
Martin Wierbosch is no stranger to the refrigeration compressor industry. Since March 2005 his company, RM Support, has been providing services for screw compressor sets in the Netherlands, where they are located, and throughout Europe. With a dedication to using new materials and creating environmentally friendly solutions, RM Support is a forward-thinking company.
What exactly does a shaft seal do and what counts as shaft seal failure?
"The purpose of a mechanical seal is to keep refrigerant inside and prevent leakage by sealing it with oil." All seals will leak a small amount of oil; however "seal failure means that the leakage is extreme and uncontrollable." It is at that point that the seal is considered broken and will need replacement, resulting in an expense for the owner.
Why do shaft seals break after a short period of use?
RM Support decided to conduct some research into this very question. After four years of research and analyzing 110 broken shaft seals, they came up with some interesting observations. One of which, was that the majority of seals (71%) displayed damage to the carbon ring, which looking at the symptoms was caused by overheating. "If we could handle the extra effects, such as generating less heat, then we could lower the number of broken shaft seals."
So, is this why RM Support decided to develop Coldores?
Yes and no. "It actually stemmed from a complaint [in the industry]", explained Martin. "The shaft seal is the weakest part of the refrigeration compressor system and by being the weakest part, it is prone to breakages." So many breakages that after some research, Martin and his team realized that one individual in the company was working exclusively on changing shaft seals. "This [the broken shaft seals] was leading to more maintenance costs than companies wanted. In addition, while the shaft seals are being replaced the machine cannot be used at that time, losing the company about four hours for each replacement. We were looking for a better solution."
While the design of a shaft seals hasn't changed over time, the lifespan of a shaft seal is much shorter than years ago. In the 1980's and early 1990's a mechanical shaft seal could last from five to ten years. Today, they only provide one year of service. Coldores, however, guarantees the longer life span of up to 3 years.
What is different about Coldores over other shaft seals?
"Thanks to a diamond layer, Coldores is super conductive; it generates 60% less heat and is the first of its kind in the refrigeration compressor industry." Coldores is also the only shaft seal for refrigeration compressors that can sustain dry running. Dry running, a condition that contributes to shaft seal failure, can be sustained by Coldores for up to 100 minutes.
Another unique point about Coldores is its assembly. "Traditional mechanical seal assembly is composed of several parts. The loose parts require a very clean and well prepared area; even the salt from your fingers can affect the installation. In addition, the traditional shaft seal cannot be used again if something goes wrong during installation or when you need to get past it to check other components of the compressor." Coldores, on the other hand, is all one piece. The loose parts of traditional mechanical seals are all built into one cartridge. The one cartridge design means that RM Support have created an environmentally friendly shaft seal that installs in one piece, is easy to put in and is exchangeable, meaning it can be re-used during thrust bearing exchange.
Is the use of diamonds for the production of a shaft seal new technology?
"Yes, in the refrigeration industry it is a completely new technology. Diamonds are extremely hard and are always able to have liquid around them. Yet, at the same time they are rough so there is a reduced amount of contact, generating less heat." However, until recently it was a challenge to utilize the technology at a financially viable level. "It was difficult but the results are good."
What would you say to people who are considering Coldores?
"Seeing is believing. Test it. We can always put your system back to how it was," although, by the sounds of things you probably won't want to go back to your old system.
Diamond Shaft Seal for the refrigeration compressor industry
