5. Temperature Controller from room temperature to 250c
Our Heated valves contain a built in Mineral Insulated tube heater.
We developed a dedicated temperature controller to comply with the low resistance heater (7 ohms) and its fast response time (20 seconds).
We strongly recommend using this controller to attain +/- 0.2 temperature control of the valve without mishaps.
The EL Temperature controller is based on the TZN4S PID controller unit, with the addition of power switch and step down transformer to fit the 7 ohm heating resistor element on the valve. Heating power is limited to 30 Watts.
The Even-Lavie valve. Assembly options. History and solutions.
For many years we had only one kind of assembly of fully mounted HT (High Temp) valve, on flange, on columns, and one assembly for RT (Room Temp) valve.
The "wings" / stubs / arms / flange, that carry the HT valve head was made of 2 mm thick S.S. The columns that carry the valve head, (and keeps stand-off of ~100 mm long) were made of S.S. too.
The insulation of the hot valve head (up to 2500 C) from the base flange - was perfect. Unfortunately, if you had to replace the sample material in the cartridge, after you shut the power down, it took 5-8 hours to cool the valve down to ~ 500 C prior to breaking the vacuum.
To shorten this time we developed another solution which gives reasonable balance between opposite requirements. Good insulation while heating, but – on the other hand- fast cooling.
We replaced the S.S. columns –with hard Aluminum, so heat leakage was still reasonable, but cooling down –become much faster. - About 45-60 Min.
The valve head can work at 250º, while mounting flange is hotter, but still safe to touch.
Optional assembly: Working on low temp. with HT valve
Since our valve is a solenoid valve, while operating the HT valve at 1 KHz, the self-heating of the valve head, without additional heating, generates some heat (The valve will self heat up to ~ 100ºC), depending on the pulse width. For some sample materials this is too high a temperature in some cases.
Because of this problem we developed another solution, which give two optional assemblies, and two different operation conditions.
We replaced the material of the "wings / stubs / flange that carry the HT valve head. Instead of 2 mm thick S.S. alloy – to 4 mm hard Aluminum.
Thermal conductivity of this construction, with Al. "wings" is of course –very good.
For low temperature operations –it is perfect, but for the HT valve, the thermal conductivity is too high. We therefore changed the construction of the support columns to lower their thermal conductivity by adding stainless steel spacers (22 mm.) to the longer Aluminum columns.
When working up to 1000C the customer should use the Aluminum spacers supplied. When working above 1000 C it is advisable to use the stainless steel spacers supplied.
One should undo and take-off one (Of 3 M-4) long screw that connects the Al. wing +one spacer + fixed column, and replace one spacer, and put the screw back, without firm tightening. Then, the same with the two other screws and spacers. After the replacement, gently tighten the 3 screws.
The maximum total stand-off that we offer to our customers – is 180 mm, from the internal side of the flange – to the top of the valve head. We do not offer longer stand-off.
If you add the 4 mm thick O-ring seal, (Comes with Al. or SS centering ring) you need to subtract 4 mm so the actual stand-off is -176 m only.
THE EVEN-LAVIE VALVE HT (High Temperature) fully assembled model
An assembly with optional high, or Low temperature operation
