HEPA Filters Leaks

[juan2025]

Dear Forum
I installed some Hepa Filter in a Laminar Flow then I performed the integrity test (DOP)and obtained bad results, I found leaks in the whole filter aprox. in 3 Inches from the frames to center of the four sides. We asked at the supplier about the case, but they assure us the efficiency(99,99%DOP)and the integrity test was performed in the factory with good results.
All the papers about the filters are OK.
The filters had been installed correctly and all the variables in the test had been re-checked.
I appreciate any input
Best Regards

Juan

 

[quark]

Juan2025!

HEPA filters may leak after installation also because of damage occured during transit and storage. If your leakage area size is not more than 1/2" length and 5mm width you can seal it with silicon sealant as per IES-CC-RP-002 and 006. I don't have those standards with me in electronic format.

I think you can be more specific about the location.

Regards,

 

[juan2025]

Quark
In a frontal view, the leaks exceed the IES criteria; are 3 Inches from the edge of the frame to the center in all the perimeter of the filter. In other words more or less 25% of the filter has leaks. I know that make the filter unusable. But we have to detect the fail.

Regards

 

[quark]

Juan!

I feel the joint of filter media with the frame of the filter might have been loosened. There may be leaks from the joint and are expanding parallel to filter face. You can try out one thing. Cover the filter area where you feel it's leaking with a plastic sheet and now check below the plastic sheet. If you still find leakage, then it may be from the joint itself. Then you can catch hold of the manufacturer.

Note: Please keep me informed for, this is a good case study and I am very much interested.

Regards,

 

[samv]

(excuse me)

what is IES?

 

[quark]

IES - Institute of Environmental Sciences (of USA)
CC - Contamination Control
RP - Recommended Practice

Regards,

 

[dpoppeli]

The filters are only as good as the seal into the frames. I also suggest this as the potential problem. Were the frames purchased/supplied from a reliable source and are they made for that particular make of filter? Do they measure square and true? Are the gaskets on either the frame or filter in good condition?

 

[juan2025]

The frames were supplied from a reliable customer and the LF were designed to be used with those filters. The filters were correctly installed and its gaskets and frames are in good condition.

Regards
Juan

 

[ROCHESTER]

What is the manufacturer and model? You say everything was supplied by reputable vendors and installed correctly. You also said the filter media is integral. Right?? If this is true, then the HEPAs aren't leaking and the DOP tests are being performed incorrectly.

But, I've seen the same results form HEPAs improperly sealed in the housing. We had a whole batch fail DOP due to bad caulking at the filter/housing seal. This sort of leak is quite easy to ID. You will get a dramatic spike in the photometer reading as you scan across the seal.

 

[EagleCove1]

What actual kinds of seals do you have on the HEPA Filters?

The mere statement of RELIABLE SOURCES can contradict the tractability of the product that is DOD rated.

This statement supersedes the DOP test protocol of the actual media and cannot be considered equal to published data. This could be perceived as a smoke screen by the installer to divert fault for possible means and methods variations of acceptable installation.

Are the filter seals Field Fabricated/ purchased and Field Installed Frame Sealed or Factory Gel Sealed?

Field Installed/Fabricated Mechanical Frame Sealed filters have been historically unreliable based on actual field particulate testing. The problem is being able to gain entry prior to contamination by a medium that will not allow safe-entry field-testing. Once the operation is started, protocol will not allow normal field testing procedures.

DOP testing via mineral-based protocol has limited accuracy based on the notable failure rate, similar to what you have noted. This has also been shown to shorten the effective life of the filter media.

In a new installation, cleanliness is usually difficult to achieve. On that basis, we have found that this is a time to actually measure the overall effectiveness of the HEPA filters and any pre-filters.

Field testing of the HEPA filter modules similar to procedures used in taking a Velocity Traverse can indicate the integrity of a filter module. However, the focus must be on the areas of the seals in the filter frames. Both tests must be performed to provide a field verification of actual PPM of particulate size based on DOP requirements of the conditions entering the filter and leaving the filter.

Filter seal leakage is the biggest cause of filtration failures. Torn or damaged media is second in my experience. Yet, it is all to common for value engineering to replace the manufactured racks to be replaced with field fabricated racks...This is the start to the road to ruin....

Test within reason and be confident....is the best prescription for this application.

 

[EagleCove1]

Please correct my mis-speak of DOD to DOP...The Department of Defense is not applicable at this time.