Date: Sun, 31 May 1998 11:06:10 +0900 (JST) From: Hans-Gerd Berns To: Bill Kropp , Hank Sobel Cc: Jeff Wilkes , Ken Young , Peter Halverson , Tomasz Barszczak , Mark Vagins Subject: radon huts status update: cooling/dehumidification system Hi there. A few days ago, the air cooling and dehumidification section in the radon hut was fixed again. It's running fine now, keeping the relative humidity level of the air pumped to the SK dome at approx. 25-30% currently (with outside air humidity at approx. 60-80%). In the summer, the humidity levels may rise somewhat, but the system should have no problem dealing with it. Last tuesday, I had arranged with the mining company (through Yoko) to have the refrigerant in the air cooler serviced again and refilled if necessary. This service was already done before not too long ago, in last September. But a few weeks ago, I found there was almost no pressure left in the refrigerant pipes and that's why the compressor was kept off due to the safety settings in the regulator electronics. The service person needed about 800 grams of R22 until the pressures in the refrigerant pipes were at nominal levels again. After the compressor started working nicely again I asked him if he could check for any possible leak in the pipes. He used a very sensitive R22 sniffer and it detected a tiny level of R22 near or at the "thermal expansion valve" next to the "chilled water evaporator" inlet. He used a wrench to tighten the pipe connections a little more and after a while the R22 detector didn't complain any further. So, he might have detected and fixed the actual leak! Though he said he wasn't quite sure and recommended to have the system checked in a couple of weeks or months again. Secondly, I exchanged the fluffy waterhose from the new sump pump location inside the tunnel with the re-ordered 25mm polyethylene pipe. Now the water pressure and throughput at the air cooler is perfect again. Last-not-least: With the last oil change at the service blower I couldn't notice any further oil loss than the usual level of a few mililiters within an oil change period (40 days) as before. I consider this as pretty normal and nothing to worry about. Though it would be nice to have a manufacturer's representative or service person have a look at it sooner or later. I mean, the blower has been running almost uninterruptedly for at least 10 months since I've got involved with the radon hut. I don't know how many hours it already has operated before that time. From the older logs it looks like possibly another 5-6 months. If you translate this with a typical preformance of a car engine, assuming you drive 55 miles an hour uninterrupted, this would be 600,000 miles! ... Regards. - Hans PS: If I haven't told you yet, you can check out the radon hut's performance and latest radon levels inside and outside the SK dome (almost) live via the web at: http://www-sk.icrr.u-tokyo.ac.jp/~berns/SUPERK/LOGS/#rnhut (use you www-sk login and password, the same as for dormitory reservation).