The temperature range, temperature stability, cooling capacity and pumping specifications are determined under controlled conditions. These include an ambient temperature of 20°C, 50% relative humidity, Circulator lid on, no external load attached, and where, within range, distilled water is the fluid medium. For temperature measurements below +5C, we use Dynalene HC50™, or 50% ethylene glycol-water mixture. Silicone high temperature fluids are used above 100°C. Your ambient temperature and application conditions may vary from our standard conditions; therefore the results may be somewhat different than published specifications. All specifications are based on actual measurements, not averages as done by some manufacturers.

1.2. How is the capacity of my circulator rated?

Circulators are often rated in Watts and BTU/hr. This is a power specification that refers to the amount of heat removed or added over a period of time. Note: Watt x 3.41 = BTUs/Hr.

1.3. What is the difference between temperature accuracy and temperature stability?

Temperature accuracy is determined by how close the indicated display agrees with an accurately calibrated standard thermometer. Temperature stability is the indication of how the temperature at a point in the reservoir varies with time or maximum deviation from average mean temperature for 1 hour @ 50°C, using water.

1.4. What is Cool Command™?

Cool Command™ is unique technology developed by PolyScience which combines microprocessor based controlling with pulse-width modulating valve refrigerant metering to provide the exact amount of cooling needed for your application. This results in more precise control, optimum cooling, and longer compressor life. Models equipped with the Cool Command system can provide cooling effects within the entire operating range of the unit. This means that a more rapid cool down from high temperatures is possible. Cool Command™

back to top of page, to 1. Circulators, Circulating Baths, Thermostats

1.5. How can the required amount of cooling or heating for my application be determined?

In many cases, the manufacturer of the device you are trying to cool will be able to tell you how much cooling (in watts or BTU's) is needed. If this is not available, contact PolyScience for help. We may already know from past experience what is required, or we can help you calculate your needs for either a circulator or chiller.

To calculate the heat load of your system, use this formula:

Watts = DT° x (K) / S

Where:

DT = The difference between incoming and outgoing tap water temperatures of your instrument. Measure carefully using the same thermometer for both locations. You may measure in Celsius or Fahrenheit.

S = The number of seconds to fill a one liter container.

K = Conversion constant for density and specific heat of water, and the ratio to convert units measured into Watts per hour for Celsius or Fahrenheit. (Measured in: Celsius = 4,186, Fahrenheit = 2,326)

Additional Considerations:

If ambient temperature of the cooling location is above 20°C, add 1% to the calculated wattage for each 0.5°C over 20°C.

If operating at 50Hz, add 20% to the calculated wattage.

If line voltage is consistently below rated voltage, or if you work at high altitude, add 10% to the calculated wattage.

Future growth cooling needs or variability of heat output of existing unit.

PolyScience is available to assist in calculating chiller size for your application.

1.6. Can I specify Cooling and Heating capacities for the same system?

Yes. The patented control techniques incorporated into the PolyScience circulators provide for seamless transitions between cooling to heating. Our refrigerated and heated combination units are specified with high precision over a wide temperature range.

1.7. How is the flow rate of the fluid in my system determined?

The instrument or apparatus that is connected to the chiller usually mandates this and specifies this in gallons-per-minute (GPM) or liters-per-minute (LPM). This is typically a minimum value required to deliver the desired heat transfer. A higher flow rate is generally acceptable. If there is a pressure requirement, use care to determine the flow at the desired pressure.

1.8. What accessories are available?

The circulators models with a reservoir have 1/4" MPT internally threaded inlet and outlet for easy attachment to external equipment. Male inlet and outlet adapters for 3/8, 1/4, and 3/16 in tubing are supplied when units are shipped, along with a reservoir cover, one 2 Ft. length of insulated Buna N tubing, 6 ft. cord with standard grounded US plug on 120V models and European plug on 240V models. Additional accessories include a remote probe in 10, 25 and 50 ft lengths for the programmable models, Digital to analog communication adapter, PolyTemp Software, cooling coils, Tubing for high temperature up to 300°C, low temperature insulated tubing, Clamps, tubing, glass thermometer, Hollow plastic floating balls for insulating open baths, algaecide and bath cleaner.

back to top of page, to 1. Circulators, Circulating Baths, Thermostats

1A. Circulators: Types of Controllers and Temperature Control

1A.1 What controller choices do I have when selecting a PolyScience circulator?

There are four choices of circulator controllers. They are Programmable, Digital, Standard and Analog. The first three are microprocessor based, Proportional Integral Derivative (PID) controllers offering high levels of stability, digital set and read display, and varying levels of operating convenience, price and features. The Analog controller is an economical proportional controller requiring manual setting of the control point and thermometer readout. All controllers have a redundant safety backup. Greater detail can be found in the PolyScience catalog or contact PolyScience for help in selecting the appropriate model for your application.

1A.2 Can I use a heating-only circulator to control close to ambient temperature?

It is possible, but not recommended for consistency. A refrigerated circulator is preferable. Controlling fluid temperature close to varying ambient temperatures requires a consistent source of cooling, preferably refrigeration, in order to have the controller work properly. A tap water cooling coil in a heating circulator reservoir usually does not provide enough dependable cooling. The cooling must overcome external conditions such as fluctuating room temperature or internal conditions such as friction heating of the bath fluid caused by the mechanical action of the pump. Friction heating from the pump and fluid, plus transfer of heat from the motor to the pump impeller can cause the bath fluid to gradually rise 3 - 15°C over time. Depending on the type of pump, the temperature rise, even without the heater on, is sometimes much more. That is why PolyScience heating circulators are rated at the low end of their temperature range as ambient +5°C. Because of the temperature variability of cooling tap water, this specification is listed without the use of a cooling coil. The type of bath fluid, effectiveness of bath insulation and use of a bath lid also are important considerations when trying to control near ambient. For best results, a refrigerated circulator should be used when working close to ambient temperatures, even as high as 35°C. PolyScience circulators feature pump speed control to allow for operation closer to ambient through reduced friction heating.

1A.3 Will my circulator maintain temperature stability on hot and humid days?

As indicated previously, PolyScience specifications are determined under standard conditions of 20°C and 50% relative humidity. If these conditions are greatly exceeded, the circulator must work harder to maintain a stable temperature. Therefore, under extreme conditions, the control stability may be reduced. If the circulator is not in an air conditioned environment, locate it away from direct sunlight or other external heating sources such as heat and air conditioning vents, that may contribute to unwanted, variable temperature control. When selecting a unit for use in a non air conditioned area above 20°C, add 1% to the heat removal requirement for every 0.5°C over 20°C.

1A.4 Does temperature stability vary throughout the published temperature working range?

No. PolyScience specifications are very conservative and you should see no variation in stability at settings within the published working range. Keep in mind that once a setpoint has been established; adequate time must be allowed for the temperature to stabilize. Depending on the reservoir size and where the new setpoint is compared to a cold or room temperature start, the time to stabilize could be substantial. Also, time to stabilize your external application must be considered.

1A.5 What should I do to achieve optimum temperature control with my circulator?

Basic steps for optimum results include the following: Keep the reservoir covered with the lid provided; insulate and minimize the length of tubing connecting the circulator with your application; increase flow by using the maximum diameter tubing possible; set the pump speed for best mixing; use a remote probe if you have a programmable controller.

1A.6 Why does an external probe used with a PolyScience programmable circulator give better temperature control at the remote application point?

Use of a remote probe permits the point of control to be switched from inside of a programmable circulator reservoir to the remote application. Because the temperature is now sensed at the point of need rather than inside of the reservoir, there is compensation for heat loss or gain between the circulator and the remote control point. These changes can result from varying room temperature, length of tubing, and changes at the point of application. Remote sensing allows for quicker response resulting in greater accuracy and stability where it is most necessary.

1A.7 Why is it necessary to specify the temperature at which the maximum cooling capacity is needed?

To achieve the desired temperature and desired rate of change. Often a system is required to go to an extreme temperature; however, it may not matter that it arrives at that point very quickly. In this case, a cooling capacity can be specified at a more conservative level, allowing for a lower power unit which may take up less space, less energy, and would be less costly.

1B. Circulators: Types of Pumps and Their Applications

1B.1 What types of pumps are offered on PolyScience circulators?

The two types available on PolyScience circulators are a pressure (simplex) pump and a pressure/suction (duplex) pump. The simplex pressure pump is typically used to push controlled temperature fluid through tubing, into the closed loop, and back into the reservoir. There is positive pressure throughout the circulating system. With a duplex pressure/suction pump, the pump produces pressure to the external closed loop application, and the liquid is returned to the circulator by the suction side of the pump. This duplex pump is suitable for maintaining liquid level in an open bath because it can return fluid to the circulator.

1C. Circulators: Bath Liquids

1C.1 Fluids Chart

Recommendations: Use distilled water for temperatures from 10°C to 90°C or a mixture of laboratory grade ethylene glycol and water for temperatures -20°C to 100°C. The fluid must be chemically compatible with the 300 series stainless steel in the wetted parts. The fluid must also be able to produce the temperature range desired.

For temperature stability of �.01°C, the viscosity should be 50 centistokes or less at the lowest operating temperature to allow good fluid circulation and to minimize heating from the pump. Most single type of fluids will be able to stabilize to �.01°C over a 100°C range. Use fluids that will satisfy safety, health, and equipment compatibility requirements. The chart below will help in selecting a fluid for your application. Stay within the fluid's normal range for best temperature stability, low vaporization, and safety. You are responsible for proper selection and use of the fluids.

Extreme range operation should be avoided.

FLUID DESCRIPTION	SPECIFIC HEAT @25°C	NORMAL RANGE	EXTREME RANGE
Water	1.00	10°C - 90°C	2°C - 100°C
Ethylene Glycol 30% Water 70%	.90	0°C - 95°C	-15°C - 107°C
Ethylene Glycol 50% Water 50%	.82	-20°C - 100°C	-30°C - 100°C
Ethylene Glycol 100%	.62	50°C - 125°C	0°C - 125°C*
Methanol 60% Water 40%	.52	-45°C - 0°C	---
DynaleneTM-HC 50	.76	-50°C - 60°C	-62°C - 60°C
DC200 5 cs Silicone Oil	.32	-35°C - 65°C	-50°C - 125°C*
DC200 10 cs Silicone Oil	.34	-20°C - 80°C	-35°C - 165°C*
DC200 20 cs Silicone Oil	.36	0°C - 100°C	-10°C - 230°C*
DC200 50 cs Silicone Oil	.39	50°C - 150°C	5°C - 270°C*
DC510 50 cs Silicone Oil	.39	50°C - 150°C	5°C - 270°C*
DC550 125 cs Silicone Oil	.42	100°C - 200°C	80°C - 232°C*
DC710 500 cs Silicone Oil	.45	150°C - 250°C	125°C - 260°C*
Fluorinert	.23	-55°C - 150°C * #9;	TBD
Galden	TBD	-55°C - 150°C * #9;	TBD

*WARNING - Fluid's flashpoint temperature. DC fluids are manufactured by Dow Corning.

DO NOT use the following fluids:

Automotive antifreeze with additives**

Hard tap water**

Deionized water with a specific resistance > 1 meg ohm

Any flammable fluids

Concentrations of acid or bases

Solutions with halides: chlorides, fluorides, bromides, iodides or sulfur

Bleach (Sodium Hypochlorite)

Solutions with chromate or chromium salts

**At temperatures above 40°C, additives or mineral deposits can adhere to the heater. If allowed to build up, the heater may overheat and fail. Higher temperatures and higher concentrations of additives will cause a faster deposit build up. WARNING: Do not use a flammable liquid as a fire hazard may result.

APPLICATION NOTES At fluid's low temperature extreme:

Presence of ice or slush adversely affects temperature stability.

Viscosity above 10 centistokes adversely affects temperature uniformity.

High fluid viscosity and high speed pumping generates heat in the fluid.

At fluid's temperature above ambient without using refrigeration:

Without refrigeration and within 15°C of room temperature, the viscosity should be 10 centistokes or less to avoid friction heating of the fluid. Heat loss is encouraged by uncovering the fluid reservoir and lowering pump speed.

At fluid's high temperature extreme:

Heat loss from vapor causes poor temperature stability.

A fume hood may be required to prevent the buildup of vapors inside the room.

Use a cover and/or floating hollow balls to help prevent heat and vapor loss.

Fluid lost from vapor has to be frequently replenished. The temperature range, temperature stability, cooling capacity and pumping specifications are determined under controlled conditions. These include an ambient temperature of 20°C, 50% relative humidity, Circulator lid on, no external load attached, and where, within range, distilled water as the fluid medium. For temperature measurements below +5C, we use Dynalene HC50™ or 50% ethylene glycol-water mixture. Silicone high temperature fluids are used above 100°C. Your ambient and application conditions may vary from our standard conditions; therefore the results may be somewhat different than published specifications.

1D. Circulators: Warranty Terms, Service and Correcting Problems

1D.1 What are the PolyScience Warranty Terms?

PolyScience products have a two year warranty on parts and one year warranty on labor.

1D.2 How does PolyScience provide service and correct problems for their units in the field?

PolyScience units are inherently reliable and require very little support once installed at the customer's site. With our past experience, supporting customers in the field usually comes down to a simple phone call to guide a technician through a few troubleshooting steps. Because of the custom designs of our units, if a unit is damaged and needs repair, it is best to ship it back to the factory. We can also contract the service of larger units to various service agencies across the nation if on-site repair is necessary.

2. Chillers

2.1 How are the published specifications for PolyScience chillers determined?

The temperature range, temperature stability, cooling capacity and pumping specifications are determined under controlled conditions. These include an ambient temperature of 20°C, 50% relative humidity, no external load attached, and where within range, distilled water is the fluid medium. For low temperature measurements lower than +5°C, we use Dynalene HC50™, or 50% ethylene glycol-water mixture. Your ambient and application conditions may vary from our standard conditions; therefore the results may be somewhat different than published specifications.

2.2 How is the capacity of my chiller rated?

Chillers are often rated in BTU/hr or Kilowatts (kW hr) or Watts. These are power specifications that refer to the amount of energy used over a period of time. 1 BTU/HR is the same as 3413 kW hr. On large systems with high BTU/hr ratings, the capacity is referred to in "tons". 1 ton is the same as 12,000 BTU/hr. Heat is also rated in kilowatts (kW). Maximum Watts of heat removal is determined by adding known watts of heat to the fluid system.

2.3 What is the difference between temperature accuracy and temperature stability?

Temperature accuracy is determined by how close the indicated display agrees with an accurately calibrated standard thermometer. Temperature stability is the indication of how the temperature at a point in the system varies with time. The design of the chiller's circulation system, location of sensors and Cool Command™ technology make the thermal fluids and therefore the stability quite consistent.

2.4 What is Cool Command™?

Cool Command™ is a unique technology developed by PolyScience, which combines microprocessor based controlling with pulse-width modulating valve refrigerant metering to provide the exact amount of cooling needed for your application. This results in more precise control, optimum cooling, and longer compressor life. Models equipped with the Cool Command system can provide cooling effect within the entire operating range of the unit. This means that a more rapid cool down from high temperatures is possible. Cool Command™

2.5 How do I determine the capacity of my cooling requirements?

Choosing the right size chiller adds to the economies of its use. The optimum size needed is based on the amount of heat your application is generating, plus additional power to maintain temperature under varying loads. The PolyScience catalog contains information and a formula to help you select the correct size chiller. In many cases, the manufacturer of the device you are trying to cool will be able to tell you how much cooling (in watts or BTU's) is needed, or we may already know from past experience what is required. If this information is not readily available, contact PolyScience and we will assist you in determining your cooling requirements.

To assist us determining the cooling capacity required, some initial information is helpful to have on hand when calling: - the difference between the incoming and outgoing temperature of the fluid temperature of your instrument , in °C or °F. - the time to fill a one liter or one gallon container - the type of thermal fluid used (even if it's water) and if possible, the specific heat and weight of the fluid Additional information may be required.

To calculate the heat load of your system, use this formula:

Watts = DT° x (K) / S

Where:

DT = The difference between incoming and outgoing tap water temperatures of your instrument. Measure carefully using the same thermometer for both locations. You may measure in Celsius or Fahrenheit.

S = The number of seconds to fill a one liter container.

K = Conversion constant for density and specific heat of water, and the ratio to convert units measured into Watts per hour for Celsius or Fahrenheit. (Measured in: Celsius = 4,186, Fahrenheit = 2,326)

Additional Considerations:

If ambient temperature of the cooling location is above 20°C, add 1% to the calculated wattage for each 0.5°C over 20°C.

If operating at 50Hz, add 20% to the calculated wattage.

If line voltage is consistently below rated voltage, or if you work at high altitude, add 10% to the calculated wattage.

Future growth cooling needs or variability of heat output of existing unit.

PolyScience is available to assist in calculating chiller size for your application.

back to top of page, to 2. Chillers

2.6 Can I specify Cooling and Heating capacities for the same system?

Yes. The patented control techniques incorporated into the PolyScience Series 5000 chillers provide for seamless transitions between cooling to heating. Our Chiller/Heater combination units are specified with high precision over a wide temperature range.

2.7 Why is it necessary to specify the temperature at which the maximum cooling capacity is needed?

To achieve the desired temperature and desired rate of change. Often a system is required to go to an extreme temperature; however, it may not matter that it arrives at that point very quickly. In this case, a cooling capacity can be specified at a more conservative level, allowing for a lower power unit which may take up less space, less energy, and would be less costly.

2.8 How is the flow rate of the fluid in my system determined?

The instrument or apparatus that is connected to the chiller usually mandates this and specifies this in gallons-per-minute (GPM) or liters-per-minute (LPM). This is typically a minimum value required to deliver the desired heat transfer. A higher flow rate is generally acceptable. If there is a pressure requirement, use care to determine the flow at the desired pressure.

2.9 How do I have to know the pump pressure [in PSI] required?

As you will see in the next question, the pressure determines the type of pump we use. It is also imperative to select the proper size of pump; all pumps are specified with a GPM at some PSI. A one-quarter horsepower pump might be able to put out 10 GPM but not with any pressure. Likewise, a similar sized pump may be able to build up plenty of pressure, yet at a very small flow rate. This is the same as specifying both voltage and current requirements for an electrical appliance.

2.10 What kind of plumbing will be used in my chiller?

This is determined by the fluid and temperature range and operating pressure. We want to be sure that we choose plumbing that is compatible with the fluid to avoid deterioration of the pipes or contamination of the fluid. For example, in a DI water system, we could use plastic pipe or stainless steel; for high temperature requirements, copper pipe or Teflon tubing would be used in place of the lower temperature rated plastics. Some customers require stainless steel for their application because of the products that it comes in contact with.

2.11 What about 110/120VAC power?

Most compressors are available for 110/120VAC but check with PolyScience customer service for the particular model you are interested in learning about.

2.12 What accessories and options are available?

Options include: Fluid Flow Meter, Fluid Pressure Meter, Particle Filter, Deionized Water Compatible, Analog Interface, RS-232 interface, Remote Start/Stop Capability, and Flourinert compatible. Please indicate, on the Chiller Quote Request Form, any items you are interested in learning about.

back to top of page, to 2. Chillers

2A. Chillers: Temperature Control and Types of Controllers

2A.1 What controller choices do I have when selecting a PolyScience chiller?

PolyScience chillers include microprocessor based, Proportional Integral Derivative (PID) controllers offering high levels of stability, digital set and read display. All controllers have redundant safety backup.

2A.2 Can I control the temperature of my application close to ambient temperature?

Controlling fluid temperature close to varying ambient temperatures requires a consistent source of refrigerated cooling, in order to have the controller work properly. The cooling must be sufficient enough to overcome external conditions such as fluctuating room temperature and internal conditions such as friction heating of the bath fluid caused by the mechanical action of the pump.

2A.3 Will my chiller maintain temperature stability on hot and humid days?

As indicated previously, PolyScience specifications are determined under standard conditions of 20°C and 50% relative humidity. If these conditions are greatly exceeded, the circulator must work harder to maintain a stable temperature. Therefore, under extreme conditions, the control stability may be reduced. If the circulator is not in an air conditioned environment, locate it away from direct sunlight or other external heating sources such as heat and air conditioning vents, that may contribute to unwanted, variable temperature control. When selecting a unit for use in a non air conditioned area above 20°C, add 1% to the heat removal requirement for every 0.5°C over 20°C.

2A.4 Does temperature stability vary throughout the published temperature working range?

No. PolyScience specifications are very conservative and you should see no variation in stability at settings within the published working range. Keep in mind that once a setpoint has been established; adequate time must be allowed for the temperature to stabilize. Depending on the chiller's cooling capacity and where the new setpoint is compared to a room temperature or cold start, the time to stabilize could be substantial. Also, time to stabilize your external application must be considered.

2A.5 What should I do to achieve optimum temperature control with my chiller?

Basic steps for optimum results include the following: Insulate and minimize the length of tubing connecting the circulator with your application; increase flow by using the maximum diameter tubing possible; use a remote/external probe.

back to top of page, to 2. Chillers

2A.6 Can I specify Cooling and Heating capacities for the same system?

Yes. The patented control techniques incorporated into the PolyScience Series 500 chillers provide for seamless transitions between cooling to heating. Our Refrigerated and Heated circulating units are specified with high precision over a wide temperature range.

2A.7 Why is it necessary to specify the temperature at which the maximum cooling capacity is needed?

To achieve the desired temperature and desired rate of change. Often a system is required to go to an extreme temperature; however, it may not matter that it arrives at that point very quickly. In this case, a cooling capacity can be specified at a more conservative level, allowing for a lower power unit which may take up less space, less energy, and would be less costly.

2B. Chillers: Types of Pumps and Their Applications

2B.1 How do I decide what pump should be used in my system?

We can determine this for you -- unless you or your application has some specific requirements. When we choose pumps for your system, there is always a trade-off between higher flow rates and higher pressures. The following chart indicates the features of the available pumps.

2B.2 What pump types does PolyScience offer on their chillers?

Magnetic Drive Centrifugal Pump "Standard" Series	Positive Displacement Pump "P" Series	Regenerative Turbine Pump "T" Series
Moderate flow at low pressure (up to 4 GPM @ 10 psi ) Quiet Operation Minimal Maintenance Corrosion Resistant	Stable constant flow at various head pressures; In-line pressure regulator adjustable between 20-100 psi Low to moderate flow (1-4 GPM) Pressure gauge included Supply coolant over long distance	Moderate to high pressure; In-line pressure regulator adjustable between 20-100 psi Low to high flow (1-9 GPM) Pressure gauge Durable and reliable

2C. Chillers: Thermal Fluids

2C.1 Fluid Chart

Plain or distilled water is suitable for many applications in the medium temperature range, and it's easy to obtain. For lower than freezing temperature ranges a 50/50 mix of water a glycol or an alcohol. However, there are many reasons not to use water: Limited temperature range (+10°C to +90°C) Ions in the water can cause corrosion and result in a build-up of residue Water nurtures organic material growth For these reasons, other fluids are used. hyperlink here to fluids

Recommendations: Use distilled water for temperatures from 10°C to 90°C or a mixture of laboratory grade ethylene glycol and water for temperatures -20°C to 100°C. The fluid must be chemically compatible with the wetted parts. The fluid must also be able to produce the temperature range desired. For optimal temperature stability, the viscosity should be 50 centistokes or less at the lowest operating temperature to allow good fluid circulation and to minimize heating from the pump.

Use fluids that will satisfy safety, health, and equipment compatibility requirements. The chart below will help in selecting a fluid for your application. Stay within the fluid's normal range for best temperature stability, low vaporization, and safety. You are responsible for proper selection and use of the fluids.

Extreme range operation should be avoided.

FLUID DESCRIPTION	SPECIFIC HEAT @25°C	NORMAL RANGE	EXTREME RANGE
Water	1.00	10°C - 90°C	2°C - 100°C
Ethylene Glycol 30% Water 70%	.90	0°C - 95°C	-15°C - 107°C
Ethylene Glycol 50% Water 50%	.82	-20°C - 100°C	-30°C - 100°C
Ethylene Glycol 100%	.62	50°C - 125°C	0°C - 125°C*
DynaleneTM-HC 50	.76	-50°C - 60°C	-62°C - 60°C
DC200 5 cs Silicone Oil	.32	-35°C - 65°C	-50°C - 125°C*
DC200 10 cs Silicone Oil	.34	-20°C - 80°C	-35°C - 165°C*
DC200 20 cs Silicone Oil	.36	0°C - 100°C	-10°C - 230°C*
DC200 50 cs Silicone Oil	.39	50°C - 150°C	5°C - 270°C*
DC510 50 cs Silicone Oil	.39	50°C - 150°C	5°C - 270°C*
DC550 125 cs Silicone Oil	.42	100°C - 200°C	80°C - 232°C*
DC710 500 cs Silicone Oil	.45	150°C - 250°C	125°C - 260°C*
Fluorinert	.23	-55°C - 150°C * #9;	TBD
Galden	TBD	-55°C - 150°C * #9;	TBD

*WARNING - Fluid's flashpoint temperature. DC fluids are manufactured by Dow Corning.

DO NOT use the following fluids:

Automotive antifreeze with additives**

Hard tap water**

Deionized water with a specific resistance > 1 meg ohm (unless DI package equipped)

Any flammable fluids

Concentrations of acid or bases

Solutions with halides: chlorides, fluorides, bromides, iodides or sulfur

Bleach (Sodium Hypochlorite)

Solutions with chromate or chromium salts

**At temperatures above 40°C, additives or mineral deposits can adhere to the heater. If allowed to build up, the heater may overheat and fail. Higher temperatures and higher concentrations of additives will cause a faster deposit build up. WARNING: Do not use a flammable liquid as a fire hazard may result.

APPLICATION NOTES At fluid's low temperature extreme:

Presence of ice or slush adversely affects temperature stability.

Viscosity above 10 centistokes adversely affects temperature uniformity.

High fluid viscosity and high speed pumping generates heat in the fluid.

3. General Definitions and Explanation of Specifications

3.1 Commonly Used Terms:

Refrigeration System: Mechanical Systems that usually include a compressor, heat exchangers condensers, and associated components that are designed to remove heat. Refrigeration systems are incorporated into PolyScience temperature control products, including Recirculating Baths, Chillers, and Immersion and Flow-Through Coolers.

Recirculation: A system of externally circulating temperature controlled fluid pumped from a PolyScience product such as a chiller or circulator. The thermal fluid flows through a customer's device or apparatus and back to the chiller for the purpose of temperature controlling the external device. The thermal fluid being circulated functions to heat, cool or maintain the temperature of the external device and then return it to the chiller or circulator, thereby recirculating the thermal fluid.

Controllers: PolyScience offers three microprocessor, PID controllers on their circulator series as well as a proportional analog controller on several additional products. These controllers combine performance and easy-to use features to maintain and adjust temperatures of the PolyScience products in heating and/or cooling functions. PolyScience chillers all include an LED set/read microprocessor controller.

Cooling Capacity: The capacity of a refrigeration system to remove a quantity heat or cool a given amount of air or fluid, usually rated in units of BTU/Hr or Watts.

Accuracy: Is how close the indicated temperature display agrees with an accurately calibrated standard thermometer at a given point, as in the reservoir of a bath.

Temperature Stability: Is the indication of how the temperature at a point in the reservoir varies with time or the maximum deviation from the average mean temperature for 1 hour @ 50 degrees C using water as the thermal fluid.

Temperature Uniformity: indicates how the temperature deviates at various points throughout the reservoir of a bath over a period of time at a given temperature using water as the thermal fluid.

3.2 What is the difference between a circulator, circulating bath, thermostat and chiller?

Circulator, circulating bath or thermostat are all names for similar devices that very accurately control temperature of fluids over a wide cooling or heating range. These devices also have varieties of circulating pumps that are characterized by low pressure and low volume. They are usually small; bench-top sized, have modest cooling capacity, include a usable reservoir and are used for controlling applications where temperature accuracy and stability are necessary. In these FAQ's, PolyScience will use the name circulator to define this type of device.

A chiller, or recirculating chiller, is also a temperature controlled circulating device, but unlike a circulator, a chiller has greater cooling capacity, is usually somewhat less accurate in temperature control, and has greater pumping volume and pressure. Because of their greater cooling and pumping capacity, chillers are larger than circulators and are usually located on the floor rather than a benchtop. The temperature range of the chiller is less than that of the circulators because chillers are optimized for high capacity cooling or use in close to room temperature conditions. Various models can also include heating capabilities.

In summary, choose a circulator/circulating bath for precise temperature control within a broad range and limited pumping needs. Select a chiller for high cooling capacity, somewhat less precise temperature control, and heavy duty pumping. We will be glad to provide additional information on these products.

3.3 What are the PolyScience Warranty Terms?

PolyScience products have a two year warranty on parts and one year warranty on labor.

3.4 How does PolyScience provide for service of their units in the field?

PolyScience units are inherently reliable and require very little support once installed at the customer's site. With our past experience, supporting customers in the field usually comes down to a simple phone call to guide a technician through a few troubleshooting steps. Because of the custom designs of our units, if a unit is damaged and needs repair, it is best to ship it back to the factory. We can also contract the service of larger units to various service agencies across the nation if on-site repair is necessary.