CCT Chamber - ACC34 Liquid Immersion - how it works
CCT Chamber - ACC34 Liquid Immersion
This optional accessory comprises of a separate holding tank (usually containing salt water) which can be heated to a user adjustable temperature up to +50°C/+122°F. Test samples to be immersed are located near the chamber base. Under programmed control the liquid is automatically pumped from the holding tank into the base, so immersing the test samples. At the end of the immersion period the liquid is automatically pumped back to the holding tank.
The control system fitted to Ascott CCT chambers enables the user to program whether liquid immersion is conducted alone, or in sequence with other climates, to form a cyclic corrosion test, for automatic execution by the chamber.
Compressed air inlet
Compressed air from a separate compressed air supply is required for the chamber in this mode of operation. This is used to open and close the pneumatically actuated ball-valves valves which control the flow of the immersion liquid between the CCT chamber and the Holding Tank. The compressed air supply should be clean, dry and oil free, pressurised to within the limits 4.0 to 6.0 bar (58 to 87 P.S.I.). Consumption is minimal.
Where a local supply is either unavailable or unsuitable Ascott offer an independent oil free air compressor as an optional accessory (ref.: ACC04). This requires connection to its own single phase electrical supply.
A separate holding tank is provided as a part of this option to accommodate the immersion liquid. This is connected to the CCT chamber by two pipes, one for delivery of the immersion liquid to the CCT chamber and one for the return of this liquid. The liquid in the holding tank can be heated to a user adjustable temperature from ambient to +50°C/+122°F. The Holding Tank is also connected to the CCT chamber by an umbilical, which provides electrical and pneumatic signals from the CCT chamber control system, to control the pumping and circulation of the immersion liquid. The Holding tank requires connection to its own 3 phase electrical power supply.
Two circulation pumps are supplied as a part of this option. One is fitted to the Holding Tank and pumps the immersion liquid to the CCT chamber, automatically, at the beginning of a liquid immersion test program. The other is fitted to the CCT chamber and pumps the immersion liquid back to the Holding Tank, automatically, at the end of a liquid immersion test program.
Forming the centre-piece of the ergonomically designed control panel is a state of the art, touch-screen, Human Machine Interface (HMI). It is here that the user controls and monitors the various chamber functions. The HMI incorporates alpha-numeric text messaging and digital displays of chamber variables such as temperature, humidity and time. Also included is a useful trend logging facility. This generates a graphical display of set values for temperature and humidity, over a 72 hour time period, and compares this to the actual temperature and humidity achieved inside the chamber, over the same period.
All chamber control panels incorporate an emergency stop and other safety facilities.
Chamber heating mats
Silicone rubber encapsulated electrical heating mats are strategically bonded to the outside surfaces of the bottom and sides of the inner working chamber. Here they radiate heat uniformly into the chamber, under the control of the chamber temperature controller. In the liquid immersion mode of operation, these heaters give the chamber a user adjustable temperature range from ambient to +50°C/122°F.
The chamber canopy is effortlessly opened/closed using pneumatic cylinders, which are activated at the touch of a button on the control panel. An automatic purge facility is incorporated to minimise the risk of corrosive salt spray escaping into the laboratory when the chamber is opened.
Strategically located sensors, mounted inside the chamber and air saturator, monitor the climate continuously and convey this information to the Human Machine Interface (HMI), where it is displayed digitally at the control panel. Temperatures are monitored by PT100 precision temperature sensors and displayed to a resolution of 0.1°C. CCT chambers are also equipped with a special design of corrosion resistant humidity sensor. This measures the relative humidity electronically inside the chamber and displays this at the HMI as %RH to a resolution of 1%RH.
Test samples are accommodated within the chamber generally by placing on, or by suspending beneath, sample racks. A full set of sample racks are provided as standard with each new chamber (see chamber data sheets for quantity) in a choice of styles. Additional sample racks are available as optional accessories, if required, as is a reinforced false floor (ref; ACC19) for supporting large/heavy test samples directly on the chambers internal base.
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