SPI Supplies^® Brand Water Chillers Recirculators

Introduction:
For years, manufacturers of water chillers offered to electron microscope and other scientific instrument users a bare bones water chiller but without many of the features necessary for the proper operation of today's complex scientific instruments. For example, the addition of a vibration eliminator on a chiller destined for use with an electron microscope, since it involved an interruption of the production line, carried a high price tag. Noise reduction packages, another feature important for electron microscope and many other scientific instrument applications similarly required the slowing down of the production run and also carried a high price tag. Low water level, high temperature and low flow alarms were also "add ons" at high premium prices.

Many years ago, SPI Supplies decided to offer only chillers that had these features built in as standard. Our production line is never "slowed down" because these features are automatically a standard part of every chiller that carries the SPI Supplies name.

Further description of the chillers:

Water chillers on electron microscopes, at least those with diffusion pumps, are an important part of the microscope laboratory. A properly selected chiller can bring the managers and workers in that laboratory years of trouble-free operation, in a low noise environment. Of course, with the trend toward turbo pumps on many of the newer microscopes being installed, the overall use of water chillers seems to be declining. Even vacuum evaporators being installed today tend to be turbo pumped instead of diffusion pumped, representing a further lessening of the need for chillers in the laboratory.

But there is still a large installed based of diffusion pumped electron microscopes as well as a large installed base of diffusion pumped vacuum evaporators. And these chillers to eventually break down and there is the need for them to be replaced. So the providing of such replacement water chillers is still an active business for SPI Supplies.

Chillers for SEM vs. TEM applications:

Until recently, the cost for a more highly controlled water chiller (e.g. TEM's needed ± 0.2C° or better) was considerably more expensive than one that was controlled to ± 1C° (which was more than adequate for SEM applications). Consequently, and again until recently, we offered two distinctly different product lines for the electron microscope laboratory, one that was lower cost for SEMs and one that was a noticeably higher cost for TEMs.

But as technology in both electronic control and also refrigeration has improved, which also means, for a given level of performance, lower cost, it made less and less sense to offer two distinctly different product lines. Today, SPI Supplies can offer the very finest ± 0.1C° temperature control for the same prices we previously offered the SEM chiller products. This has great benefits for our customers, one obvious one being that the same chiller could be used with equal levels of performance, on either a TEM or SEM. It also means we need to incur the cost of carrying in inventory only one line of products, not two. And this is yet another reason why our customers enjoy lower prices.

Vibration elimination feature:

This is a unique damping device that smoothes out the small pulsations in water flow, eliminating a source of image instability and resolution loss in the final image.

Safety interlock feature:

This feature is critically important to protect the valuable scientific equipment in our customer's laboratories and to reduce the chances that they will be facing some day a large and otherwise unexpected repair bill that could run into the thousands of dollars, all because their water cooling failed. There are three major parameters that are important for a water chiller: water temperature, water level, and water flow. All SPI Supplies chillers have built-in and as standard equipment this safety interlock feature. Because of the variety of different instrumental configurations, the chiller has a contact closure signal, which the customer can use in conjunction with the microscope interlock systems to shut down the instrument in case of cooling failure and prevent damage from occurring.

Noise and sound considerations:

The issue of noise levels is perhaps one of if not the most important concerns of prospective customers contemplating the purchase of a water chiller. This is especially true of any electron microscope application because the unit often times must go into the same room as the microscope and operator. After spending a day working in the presence of a noisy water chiller, even the most sane of minds can start to go a bit crazy. We know that from our own experience. And that is why the SPI Supplies chillers have been designed for low noise levels, which is accomplished by a combination of the use of extra sound proofing materials on the metal cabinets and the water pump (major source of noise). Another source of noise is the fan needed for cooling, and other than selecting fans that are designed for low noise operation, there is not much we can realistically do about such fan caused noise.

In-line particle filter:

There are a number of reasons why an in-line filter is useful. For one thing, if the filter starts to suddenly start collecting large amount of particulate debris particles, this could be indicative of an electro chemical reaction occurring somewhere in the system, something that if not followed closely or stopped could end up ruining the microscope or other instrument being cooled. Secondly, it removes particles from the cooling water stream that could otherwise cause harm to the microscope.

Pressure and flow control and monitoring:

One normally does not appreciate the importance of this standard built-in feature until they start the installation and find that without these features, they don't have the slightest clue as to the pressure or flow rate, or how close the pressure and flow rate come to meeting the manufacturer's specifications for the microscope. On the SPI Supplies chillers, it is always possible to independently control and monitor the pressure as well as the flow rate. Our customers tell us these features reduce dramatically the time needed to perform the installation and get the microscope up and running.

Large fill-ports:

Ease of filling the reservoir is another advantage of the SPI Supplies chillers over competitive units. Many other units has fill-ports that are only 1" in (25.4 mm) diameter but the SPI Supplies chillers have diameters of 3" (76.1 mm).

External reservoir drain port:

Most users of other chillers find it incredibly inconvenient to change coolant fluid for periodic preventative maintenance programs and consequently, as a result, preventative maintenance programs tend to be either put off or forgotten, with the end result of premature chiller failure and/or possible damage to the microscope. We have studied this phenomenon and have concluded that the best way to help our customers is to build in an external reservoir drain port. This makes changing out the cooling fluids easy and convenient, and without the need for disconnecting the chiller from the microscope, and we also find that there is a higher level of performance of preventative maintenance programs, resulting in longer unit life.

Summary of standard built-in features not found generally in other chillers without special-ordering it as an option item:

We want to stress that all of these build-in "features" mentioned above, in general, are not "standard" in any other line of chillers and while some can be special ordered, the cost to get them in a system will be significantly higher than the prices of SPI Supplies.

Voltage conversion considerations:

All cooling capacities are based on operation at 60 Hz. For operation at 50 HZ, the cooling capacity has to be reduced by 17%. We are assigning the chillers on the assumption of 220v or 240v 50 Hz operation which would mean that the chiller for 60Hz operation would in fact be slightly oversize. But this also leaves the flexibility for adding some other instrument to the cooling line such as a vacuum evaporator.