Unusual leak on Dry Sprinkler System proved hard to find

Ever since a Dry Sprinkler  Fire Protection System was installed at Alcoma Plaza in Penn hills it has been a problem for the owners .
The problem  is a very poor installation by a less than reputable well known North Hills  Contractor  of   the compressor system which was rough handled  when first installed and without proper electrical safety controls.
 The first problem was that the compressor had a 3 phase motor and was installed with out a motor starter contactor to protect the electric motor which had to be replaced after the power single phased during a  thunder storm.
The second problem was the system always seemed to loose air and compressor had to run several times a day instead of once a day.  and the third problem was the Drip Drum which collects condensate from the dry pipes was installed in an unheated room  which if it was not kept properly drained during winter would fill with water and freeze up and break flooding the building.

New system being  installed

After this happened several times  the owner asked me to look into why the system kept having problems I showed him the above problems and we put a plan of action in place.

First I installed a new 3 phase motor with proper fuses and motor starter contactor.
Next I arranged to come in monthly and drain the drip drums.
This helped tremendously but at least once  a year we would still get the system dumping the air and flooding the pipes but luckily not the stores  like it did in the past every summer . But we could never find what was causing it  other than compressor shutting off during a bad storm and needing reset yet that much air leaving system should not be happening.
The final straw was last week it dumped again but this time when I got there and let fire dept in there was a very bad smell in building I noticed it right away bad air from system but where was it leaking from.
I explained to the fire chief who was complaining the whole time they had to respond that there had to be a massive loss of air and that's what we where smelling was that old foul air from the dry pipes which got me thinking we had a bad over pressure relief valve on system  . He looked at me like I was some kind of  asshole making a statement like that but I have been working on air systems for many years so It was egg on the chiefs face when after I did a complete leak test on system with sprinkler company  that we found a hair line crack in the compressor air tank .
Which made the chief look like the ass.There was a massive air loss going on.
 They wonder why I will have nothing to do with fire depts in Penn Hills any more  well every time 223# starts there shit and keeps running their mouths and making snide remarks and alienating people in this town its no wonder they can not find volunteers and depts have a hard time raising funds.

After very carefully looking the tank over the sprinkler tech found the hair line crack right at where the mounting  foot was welded to the tank. He found it  after increasing  the tanks air pressure and checking it for leaks when he could not find them anywhere else on system and what he found  was happening was the tank would stay sealed but as it got hotter outside and in the building the tank would expand and let off its air it was holding   and it was almost 90 degrees  that day  the night the tank let loose  of its air which we could smell all over building,  but by time we got there and started checking  the tank has cooled down  looses its expansion and it looked OK and would pump up. So problem solved  with some good old detective work and a new tank now installed that will hopefully be the end of the problems with the system for a long time and result in less condensate in pipes and a lower electric bill as compressor will not have to run as much.