Temperature Applied Sciences

What is a Test Chamber or Test Room?
An Environmental Test Chamber combines the functions of an Oven and a Freezer. In its simplest form, a thermostat allows you to select any temperature within the machine's operating range. The chamber subjects the Item(s) Under Test (IUT) to various temperatures to ascertain the effect. For example, certain types of electronics and LEDs stop working at high temperatures.
Chambers come in various sizes and temperature ranges - check out our Series 3, ECO and Micro ranges.
An Environmental Test Room (or ETR) is just a large test chamber - usually fitted with a personnel Access Door.

What is meant by Climatic or Humidity?
A Climatic Chamber or Climatic Test Room adds the ability to control the Percentage Relative Humidity (%RH), or how wet or dry the air is. High humidity levels are useful for checking how 'weatherproof' your product is. Low humidity levels are useful when ramping temperatures up and down, to reduce the possibility of condensation forming. The Humidity can be generated by several processes, such as steam or water spray. The TAS climatic chamber system raises the humidity with minimal heat input, making it very efficient. Also, there is only one moving part for unbeatable reliability. Humidity is removed by the refrigeration system and the water is recycled (although as an option it can be drained to waste).
TAS Climatic Test Rooms use slightly different methods, such as Vapour Phase Generators and Rotary Desiccant Driers.

What is a Control System?
All Environmental Test Machines are fitted with a Process Controller of some type and we refer to the Required Temperature as the Set-Point. The Actual Value measured in the machine is the Process Variable. It's the Controller's job to heat or cool the machine until the Process Variable (PV) matches the Set-Point (SP). Climatic machines add the Humidity PV and SP and Altitude chambers add Pressure. More variables can be added.
Temperature is nearly always measured by a Platinum Resistance Thermometer or in very special circumstances a Thermocouple. The two devices work on different principles but achieve the same result.
Humidity is nearly always measured by a Capacitance Sensor or occasionally using Wet & Dry bulb; a second Temperature sensor covered by a close fitting cotton sock, kept damp. The latter is used if the Item Under Test gives off noxious fumes, such as uncured Silicone Sealant.
The simplest form of controller is Single Set Point - the SP is entered by hand (usually by a combination of Up & Down buttons) and the PV will change accordingly.
If you want the machine to automatically change between various set-points, a programmer is required, such as our HMI.
This allows the machine to Ramp to a set temperature (or humidity, pressure etc) in a set time, Hold at that condition (if required) and Ramp again. The sequence can be repeated for a set number of Cycles, or run continuously.
The Programs can be very simple or complex and comprise many Steps or Segments. The TAS HMI can store 180 Segments.
These can be split into different pages or programs and given unique names.
The HMI can automatically change the temperature, humidity and pressure (if fitted) at the same time, to mimic an aircraft's accent and descent through the atmosphere, for example.

What are Conditioning Units?
Sometimes the Item(s) Under Test won't readily fit inside a Test Chamber or Test Room, or perhaps it's mounted on a Shaker, or two Shakers.
A Conditioning Unit System allows for an insulated box to surround the item and be connected via flexible hoses to a remote machine conditioning the air.
The box can be manufactured by the end user, if desired, and many such enclosures of various shapes and sizes can be economically constructed.
TAS offers two types of Conditioning Unit - Mobile for enclosures up-to about 3000 litres and Fixed Conditioning Units for anything larger.
Unlike a Test Chamber or Room, an Enclosure will not be well sealed against the ingress of damp air, which can cause ice build up.
TAS has several methods to mitigate this, such as a 'wasted' system, using very dry air or automatic defrost / change-over.

Tell me about ATEX and Increased Safety
Sometimes the Item Under Test can present a hazard, perhaps it contains volatile chemicals.
In this case, the Test machine must be fitted with devices to minimise the risk of an accident.
TAS offers various systems to accomplish this, for example Indirect Heating using a thermal fluid.
Sensors such as PRTs and Thermocouples are isolated from the working chamber by Zenner Barriers and Galvanic Isolators.

What is Mechanical Cooling?
The most common type of cooling system fitted to TAS machines is Mechanical Refrigeration or Compressor Cooling.
In its simplest form, there are six components:-
1. The Compressor or 'pump' circulates the Refrigerant around the system.
2. The Condenser or 'radiator' dissipates heat energy contained in the refrigerant into the air (or chilled water circuit).
3. The Drier filters the refrigerant.
4. The Metering Device forces liquid refrigerant into a gas.
5. The Evaporator or Heat Exchanger uses the refrigerant gas to absorb heat from the chamber.
6. Lastly, the Refrigerant, which is a chemical compound that is used to transfer heat energy from inside the chamber to outside.
Depending on the operating range of the machine, Single, Dual or Triple refrigeration circuits are used.
The Dual and Triple systems are in a cascade arrangement, whereby the first system extracts heat energy from the chamber and is passed to the other systems before being dissipated.
Cascade systems use refrigerants with different properties, in order to achieve temperatures below -40ºC.
The TAS Series 3 VLT Chambers and Thermal Fluid Systems can achieve -120ºC using mechanical refrigeration alone, without the use of Liquid Nitrogen (LN2).

What is LN2 or CO2 cooling?
Gaseous Cooling is the alternative to Mechanical or Compressor systems.
It is sometimes preferred when very rapid changes in temperature are required such as Thermal Shock and Environmental Stress Screening.
Liquid Nitrogen (LN2) is supplied to the machine from either a portable, vacuum insulated Dewar or an External Supply Tank and associated Vacuum Insulated Pipework. The latter can be very costly to install, whereas the former must be re-filled regularly, depending on the testing schedule.
Liquid Carbon Dioxide (CO2) is sometimes used instead of LN2. Whilst it cannot achieve such low temperatures, CO2 is a more efficient cooling method and the cylinders do not 'lose' their content with time, unlike LN2 Dewars.
Whilst Gaseous Cooled machines are undoubtedly cheaper to purchase than their Mechanically Cooled counterparts, their running costs can quickly mount up as the LN2 or CO2 once used is given up to the atmosphere and not recycled.

Why is good ventilation important?
Apart from the Gaseous Cooled machines, all TAS products require good ventilation.
During operation and especially when cooling down, a significant amount of heat energy is expelled to the local ambient.
Unless the machine is cooled by water, this energy will cause the ambient temperature to rapidly increase, unless good ventilation is provided.
Sometimes, localised Air Conditioning is necessary. High ambient temperatures will cause a significant loss of performance.
If this is not possible and high ambient temperatures cannot be avoided, water cooling can be fitted, which uses a Chiller located externally.
More-often in these cases, the entire refrigeration plant is located outside, in a weatherproof enclosure. This is very common with Environmental Test Rooms, Fixed Conditioning Units and Large Altitude Chambers.

What is F Gas?
All TAS machines fitted with Mechanical or Compressor cooling systems will contain refrigerant gas, a controlled substance.
The rules regarding regular leak checking are governed by the F Gas regulations.
These tend to differ from territory to territory thus, rather than provide out of date information, please refer to your local government's website.
Regular leak-checking by trained and certified engineers is a legal requirement in nearly all cases.
Older machines may contain a prohibited refrigerant. You can still use the machine, as the gas is safely contained within. However, in the event of a breakdown, it may not always be possible to use the same type of refrigerant during the repair. In this case the engineer, by law, must remove the old refrigerant for safe disposal. Often, but not always and depending on the age of the machine, a modern refrigerant can be used instead, with none or minimal modification. Sometimes there may be a lack of performance such as a slower ramp rate or a reduced minimal temperature.

Why should I get TAS to service my machine?
All TAS machines are built in our factory in West Sussex, UK. Our service engineers train in the factory for at least 5 years, in many cases they actually built the machines they subsequently look after. There is no-one better than a TAS Service Engineer to service your TAS machine. They have access to the build records and in many cases have the correct spare parts with them. Yes, we may not be the cheapest and yes, you may find a local refrigeration engineer who is qualified. However, Environmental Test Machines are very different from the majority of refrigerated equipment, such as Air Conditioning, Cold Rooms, Chillers and Freezers. This is especially true for machines which operate below -40ºC as these use high pressure refrigerants which can be dangerous without the proper training and experience.

Does the machine come with a Calibration Certificate?
In the case of new machines, yes, unless stated otherwise.

Do TAS offer Extended Warranties?
Yes. The cost is dependent on the machine ordered and the warranty must be purchased at the same time as the machine.
It is not possible to provide extended warranties once a machine has been used.

What is the Annual Service cost?
This depends on the machine and whether F Gas regulations stipulate six monthly leak checks are necessary.
Please contact us for a quotation.

Does the machine need to be installed or commissioned?
In the case of Series 3, ECO and Micro chambers, no, the machines are 'plug and play'.
Humidity chambers will require good quality de-ionised or distilled water, or if Mains Fill Option is selected, the supplied hose will need to be connected to a potable mains water supply tape. These machines MUST be connected to a waste water drain, at low level.
It is NOT PERMITTED to connect a mains water fill machine to the mains water supply unless it is connected to a waste water drain.

Do Test Rooms and other machines need to be installed or commissioned?
Generally, all machines other than standard test chambers will need to be installed or commissioned by TAS engineers.
This requirement will be communicated to you during the quotation and ordering process.

Do the chambers come with shelves?
Yes the Series 3, ECO and Micro chambers come with at least one shelf as standard.
Additional shelves are available to purchase at any time.

Can I have Access Ports larger than 70mm?
In most cases yes - just tell us what you need.

Who is responsible for unpacking and siting my standard Test Chamber?
You are - unless you pay for us to attend site and commission the machine.

I have a humidity chamber. What water does it require?
Only ever use good quality, de-ionised or distilled water.
Never use tap water (unless you have a Mains Water fill system, in which case always ensure your cartridge is in good condition).

What size is the mains water connection hose for my humidity chamber?
The hose is 3m long and is 3/4" BSP female.

Can I operate my machine remotely?
Yes, if fitted with the latest HMI. You will need to connect the machine to your local network and allow outside access.
The HMI is fitted with a VNC server. Install a VNC viewer on your device (Laptop, PC, Tablet) and enter the IP address of the HMI.
You can now operate the chamber as if you were standing in front of it.

What Plant Growth Lights do you fit as standard?
We don't have a standardised lighting system as this depends on what you need the machine for - Plant Growth, Insect Studies, Photo-stability etc.
Please tell us what you require.

Do you supply chambers from stock?
Occasionally, yes, Sometimes we may have a cancelled order or a production run in progress.
If your requirement is urgent, we can often provide a hire chamber at reduced cost, during the build process.

What are your lead or delivery times?
Generally 8 to 10 weeks for standard chambers, but this varies on the type.
If your requirement is urgent, we can often provide a hire chamber at reduced cost, during the build process.

Do I need a special power supply?
This depends on the size and specification of the machine.
Some of our smaller Series 3, ECO and Micro chambers will run from a standard UK 13 amp socket.
If you have power supply restraints, let us know - we can often help.

Why should I choose TAS as my Test Solutions Partner?
Our roots go back over 50 years to 1969.
In that time we’ve accumulated vast knowledge and experience.
All of our products are designed and manufactured at our factory in West Sussex, UK. The vast majority of our suppliers are also UK based.
We have customers across an incredibly diverse range of industries and organisations.
Quotations are, of course, free and we would be delighted to talk with you over the phone or in person.