jeffrey.bartlett@LIGO.ORG - posted 06:25, Thursday 02 March 2017 - last comment - 17:14, Thursday 02 March 2017(34525)
Fire Pump Running all Night
At 14:06 (06:06 PT) Richard shut off the main fire pump (in the Carpenters Shop) which had been left on after Tuesday maintenance. The 40 to 200 Hz Breathing Noise appears to have settled down and the range has moved up to 64.2 Mpc.
The impact of this pump in the 3-30 Hz blrms in the LVEA is very dramatic and coincident with the range degradation and recovery.
Are there any other pumps we can turn off to gain some more megaparsecs? :)
Clarification;
There are two different pump types on the fire protection system. A small pump (1/2 horse power?) maintains the system pressure between 75 and 90 psi. If a fire hydrant or sprinkler system is opened, this small pump cannot maintain the pressure. At this point, pressure switches will bring on one or both of the 50 horsepower pumps (2). These large fire pumps have no remote or automated mechanism to shut them down once running. There are relief valves which spill water on the ground to prevent the pumps from overheating. It looks like we pumped about 700 gallons onto the ground last night.
Most likely the fire department was on site testing the LSB sprinkler system and caused the large pumps to start up. Normally someone in the OSB notices this extra noise and the pumps are then shut off. Richard manually shut the pump(s) off at 6 am Mar 2.
The pressure plot shows the pump running from 2pm Mar 1(Wednesday) to 6am Mar 2 local time.
Heather, Sheila
Here is a comparison of the spectra of DARM and the ITMY seismometer with the pump on and off. There is no coherence between the ground and DARM.