Seal leak detection strategies 2

[geesamand]

Hello,

My company provides machines that include mechanical seals in many situations. We always buy the mechanical seals and bundle them into our product. Our policy has been that any seal "support" items come from the mechanical seal OEM.

Today we are looking at leak detectors. Specifically to capture leakage coming off a horizontal shaft sealed with a single hard-faced mechanical seal. The product will be unrefined petroleum over a very wide range of ambient temps. The reason for leak detection is because it's outdoor equipment and frequent walkabout inspections are impractical. Our initial design for the leak detector from the seal OEM was expensive and rated to contain a small bomb. I don't have much appreciation for the size, cost, and complexity required to detect a leak dripping into a protected but not sealed housing but my gut says less than that. This is reinforced by the notion that the seal OEM has little incentive to keep costs down now since they have already sold the seal.

So I can either go with the seal OEM's system and try to gain a little more appreciation for it's robustness and features, or find something simpler from another party to ensure we're working with a design that will be successful. Please advise your opinions.

Thanks,

David

 

[flexibox]

David
In using a single seal, any leakage will drip into the drain cavity to atmosphere. In this arrangement the leakage detection vessel/container need not be designed as a pressure vessel. A simple pot with a level switch or transmitter will suffice. The issues I see is that if you want to contain it in the event of a seal failure, then you need a secondary seal and the leakage detection vessels needs to be designed to the system pressures. In this arrangement you contain the leakage and detect small leakages too. The secondary seal can be a dry running back up.
If you define your needs in full we can make recommendations.

 

[geesamand]

I see no issues with being a vented catch can as we're collecting from the seal's drain port, which is already open to atmosphere. This won't be used with double seals.

In this application, I'm told that the normal visible liquid leakage is nearly zero. It evaporates. Are there any risks with using a smaller can size (say .25L or 0.5L) versus the 4L I'm accustomed to seeing?

Thanks,

David

 

[flexibox]

Personally I would not go below 4 ltr capacity.

 

[geesamand]

That could be a major complication in our situation. We would need to locate the container external to the machine and it will be subject to the full range of ambient temperature extremes, probably necessitating an enclosure or heating elements.

Can you detail why smaller containers are not preferred?

Thanks,

David