General EPMA > EPMA Laboratory Planning and Design

Building water specs?

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Anette von der Handt:
Hi,

the topic of water purity just came up (in the 11th hour of the planning process for the new building) and I wonder if I should have an opinion on it (some others had, so it may still all change).

I will have processed cooling water and a water-to-water chiller (not bought yet, currently water-to-air Haskris) in the building and I vaguely remember someone telling me about problems with their processed cooling water.

Is this something to keep track of?

The current proposed system would have the following specs:

System shall provide water meeting reagent grade III water per NCCLS/CAP specifications:
Resistivity:                    ≥ 0.1 megohm - cm at 25°C
Silica:                           ≤ 1.0 mg/l SiO2
pH:                               5.0-8.0
Microbial:                      none

Thanks for any insight!

Probeman:

--- Quote from: Anette von der Handt on July 22, 2015, 04:18:26 PM ---the topic of water purity just came up (in the 11th hour of the planning process for the new building) and I wonder if I should have an opinion on it (some others had, so it may still all change).
or any insight!

--- End quote ---

I can't provide any process loop water specs, but I can tell you about our experiences at UofO.

We also utilize a separate water cooled chiller for each instrument, each which is cooled by a large process cooling water system. The critical aspect to this external process loop cooling water (supplied to these separate chillers), is reliability.

We had several failures of the external process water cooling pump, and though the separate chillers on each instrument continued to run, they slowly start warming up.  It take a while, but then all hell breaks loose on individual systems.

The key fix is a flow alarm that initiates an automatic phone call to selected individuals warning of a process water flow failure. Right now it notifies the local facilities people and our instrument engineer cell phone.

The only other advice I can give is to use the purest water for the individual instrument water chillers. We use pure RO (reverse osmosis) water and we never get algae or corrosion. Note that to prevent algae growth you want to block all sources of light and utilize only black rubber hoses. If you don't do this you will get awful algae growth, even in pure ethylene glycol- believe me- I've seen it myself!

Anette von der Handt:
Thank you!

That is very useful information. I passed on the recommendation for a flow alarm.

Anette von der Handt:
One follow up question: Is the flow alarm part of the chiller system or is it a third party part?

Thanks!

Probeman:

--- Quote from: Anette von der Handt on June 21, 2016, 08:43:09 AM ---One follow up question: Is the flow alarm part of the chiller system or is it a third party part?

--- End quote ---

It's a little hard to explain. 

First they had a large closed loop cooling water system for a laser lab in a nearby building. It had it's own pump and flow alarm. But this system had a huge excess cooling capacity.

So because we needed a building closed loop water cooling system for our e-beam instruments, they added a *new* closed loop connected to the first one through a heat exchanger, again with it's own secondary pump- but at first they forgot to add a separate flow alarm for this new secondary closed loop cooling water system.

When that secondary loop pump failed (Murphy's Law), there was no alarm until some of the instruments started complaining about the water inlet temperature to the individual instrument chillers.

So they added a second flow alarm to the secondary closed loop pumping system and now all is fine.

I don't know anything about the specific flow alarm systems they used (it was a facilities issue), but I expect they are just off-the-shelf items.
john

On a slightly related note, the "Sensaphone" units we use for calling us when there's a power failure (or the P-10 gas drops below 500 psi):

http://probesoftware.com/smf/index.php?topic=752.msg4686#msg4686

also have a number of "built-in" alarms... for example, a loud noise alarm (using a built-in microphone), and a water flood alarm (using a small water sensor that sits on the floor).

Both have been separately triggered by various appropriate equipment failures and hence saving us much cost and repair work!
john

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