Problems with low-temperature valve coolers
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Both BS6364 and MSS SP-134 in the low-temperature valve standards specify the extended dimensions of valves with and without cold boxes, for those equipped with extended valve stems. Excuse me, what does this cold box mean? Why is the cost twice as high for those with a cold box? I hope an expert can give some advice. Thank you!
A cold box is a plate-fin heat exchanger with high heat exchange efficiency; since its temperature is usually very low, it is placed inside an iron box filled with perlite in order to prevent loss of cooling capacity – and this is what constitutes a cold box. As for the factor of 2 higher, it might be due to its lower operating temperature; this is not quite clear, so we’ll have to wait for someone who knows the answer to explain it.
First, consider the distance between the valve arrangement (used in the cryogenic box) and the cryogenic box panels; it is quite far. Second, the insulation materials used are different: pearlite sand is used for the cryogenic box, while vacuum tubes or foam glass are used for those not intended for use in the cryogenic box~~