Value of a Polycold

Value of The Polycold on a Vacuum Coating System 
How is a Polycold similar to a shot blocker in the NCAA Basketball Tournament


One principal of high vacuum that is easily understood is the concept of water vapor in a vacuum chamber. If you live where I live in the deep south part of the USA, humidity or water vapor in the air is easily understood. Obviously, this water laden air is also in the vacuum coating chamber, lining the walls and surfaces of the vacuum chamber. 

When a chamber is pumped to a pressure of 10-3 torr or below, most of the chamber’s volume gas has been pumped away and water vapor becomes the predominant gas within the chamber. At this point the reduction in pressure is controller by the rate of water being desorbed from the surfaces inside the vacuum chamber and that water molecule finding its way to the inlet port of the high vacuum and being pumped out of the chamber. More than likely, a water molecule desorbing will simply find its way to another surface inside the vacuum chamber to again re-sorb on the surface.

So where is the basketball shot blocker reference? 

Imagine a three point shooter in basketball. The best player makes 40% of his shots and he is highly skilled. Compare that to a water molecule in a vacuum chamber that is not highly skilled at all to find the inlet to the "basket" in a vacuum system or better known as the inlet to the high vacuum pump. So what we need is better skilled water molecules able to land in the inlet? Well yes but scientifically not practical.

The Polycold coil inside the vacuum chamber acts as the shot blocker. With the coil cryogenically cooled, any water molecule moving off the surface has a much better chance to hit the Polycold coil than the inlet of the pump. The more surface area of the coil, the better chance to be "blocked" and trapped by the cryogenic Polycold coil. Once trapped on the Polycold coil that water molecule is no longer "in play" inside the chamber and stays on the coil until the next regen cycle.

Installing a Polycold in your high vacuum system pays great benefit in reducing the high vacuum pump down time of the chamber by up to half. This can result in extra coating runs per day and thus more $$ profit.

Schoonover can work with you to provide a turn key solution that includes, rebuilt Polycold, coil design, coil fabrication and installation.  Utilizing a rebuilt Polycold instead of new provides a long-term "good as new" solution with a total price (Polycold, coil and install) usually at or less the cost of a new Polycold. So more bang for your vacuum pumping buck. Visit us at and contact us for more information on this cost saving addition to your coating system.