PSN-L Email List Message

Subject: Re: geophone too close ?
From: ChrisAtUpw@.......
Date: Mon, 30 Apr 2007 14:43:11 EDT


In a message dated 2007/04/30, carpediem1@......... writes:

> Avoid using foams or Styrofoam as they have minute air pockets in them and
> as pressure changes, they will expand or contract and these changes will be
> transmitted to the instrument.

Hi Bob,

       Have any problems of this sort been actually documented? We have been 
using Cellotex cases for years apparently without problem. This is a sealed 
cell styrofoam with two layers of glass scrim glued to the surfaces. I would not 
rest my seismometer on such, but I would not expect any problems with a 
Cellotex case which is supported on the floor. The total mass is low. 
       How would this be transmitted to the instrument? 

       Regards,

       Chris Chapman   
In a me=
ssage dated 2007/04/30, carpediem1@......... writes:

Avoid using foams or Styrofoam=20= as they have minute air pockets in them and
as pressure changes, they will expand or contract and these changes will be<= BR> transmitted to the instrument.


Hi Bob,

       Have any problems of this sort been=20= actually documented? We have been using Cellotex cases for years apparen= tly without problem. This is a sealed cell styrofoam with two layers of glas= s scrim glued to the surfaces. I would not rest my seismometer on such, but=20= I would not expect any problems with a Cellotex case which is supported o= n the floor. The total mass is low.
       How would this be transmitted to the in= strument?

       Regards,

       Chris Chapman

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