Clean Room Dehumidifier

[CraigRochester]

I have a vial washing machine that uses hot water spray. Vials go in and out of the machine through "mouse holes". The aerosol laden and ~ 100F/100%RH excapes into the class 10K zone --> not good. This was not considered in the room/equip design.

I cannot ventilate normally with ducted exhaust because the duct would obstruct the HEPA coverage above and along the floor would be a tripping hazard.

I'm thinking of a refrigeration dehumidifier with ~20 CFM flow. I would direct the dry cool air back to the room and drain the condensate/aerosols.

Does this exist? Any other ideas?

Thanks in advance,

Craig

 

[quark]

That raises few questions from general convention.

1. Why is your washing area class 10K instead of 100K?
2. Suppose if you have a continuous line from washing to sealing, was there no sterile partition after tunnel?
3. Do you have any limit for washing area RH?
4. Generally, class 10K needs not more than 25% filtration ceiling. How the exhaust duct obstructs it?

General arrangement is to duct the exhaust (about 100 to 200 cfm, depending upon the speed of m/c and size of vial) with a U seal and draining the condensate to the drain pan of the washing machine.

Not a big problem with aerosols as they are washed down.

You can cool it and discharge into the room but you can do it even at your AHU cooling coil. I didn't see such a setup, sofar.

 

[CraigRochester]

Hi quark,

I wasn't here during the design. The room itself is 100K but has a full coverage zone above the washer.

1. Overkill
2. Yes, feeds a depyro tunnel
3. Room dehumidification control = 60%RH, 70%RH alarm
4. I aggree, but full coverage is installed.

The aerosols and condesing vapor is causing a mess as it exits the opingings.

Thanks for the "100 to 200 cfm" guidance.

Craig

 

[quark]

One more question. Is your machine hooded or not? If no, then my first suggestion is to cover it with acrylic (to maintain visibility) and then take the exhaust. You can take care of aerosols to some extent by maintaing laminar velocity at the exit. This requires about 1ft dia. duct. Take as big U loop as possible to cool down the moisture and collect in the drain pan. Your AHU should take care of the moisture content (after providing the drain) and 70% shouldn't be a problem.

Once you check the exit temperature of , consider it to be fully saturated, check the moisture (in grains) and see how the room air dilutes it.

Just out of curiosity, what are doing with the exhaust air from preheating zone of the tunnel? Are you leaving it into the washing room?

First wash by PW are recycled WFI (generally cooler) should take care of the solid particles.

Suggestion: If you have serious problem with vials, this is the right time to speak to the manufacturers. I never had big problems.

Regards,

 

[lilliput1]

I suppose it would be like a conveyor type automatic dishwashing machile that has exhaust hood over the front entrance opening and over the rear discharge opening. A particular model uses 16"x4" hood opening 300 CFM at the front and 16"x4" hood opening 600 CFM at the rear. Air velocity is 675 FPM and 1350 FPM respectively.

For your case then size the hood to be 4" x W+4" where W is the width of your vial in inches. Then use 675 FPM and 1350 FPM at the front & rear opening respectively.

Provide enough makeup air, cut down the return air and increase the outdoor air (OA) of the AHU serving the space. The AHU cooling load will increase because of the added OA.

 

[CraigRochester]

Let me see if I can post some sketches...

 

[CraigRochester]

[ul]
[li]The washer is hooded with acrylic[/li]
[li]Exhaust ~ 100-120F, dependent on flow out[/li]
[li]I haven't looked at the tunnel ventilation, but I don't think there is an exhaust; air is recirculated. The cooling section has a big HE for cooling[/li]
[/ul]

I don't think there is any problem with the HVAC system handling the dehumidification load. It's just the aerosols and condensing vapor causing a mess in the room.

 

[quark]

Craig,

When the system is hooded, you can take care of other things by providing an aspirator with a U loop and a filter. The aspirator capacity for washing machines upto 300VPM (say 10ml) is not more than 200 cfm as you have to only take care of the vapors.

Generally, preheat zone of the stirrer is leaked into the washing area and cooling zone is leaked into the filling area to maintain the pressure differential across the tunnel. There are different thoughts on where to leak but this is the most widely used principle.

Before fixing the aspirator capacity, just check whether you are leaking air from the preheating zone to the washing machine. This flowrate also should be added to the capacity.

Another question. Is your conveyor to ST covered or open? If it is open then better cover it (acrylic will do)so that you can maintained washed vial cleanliness and restrict the moist air flow out as well.