TB Infection Control

Hi Dr. Paul J.,

Just to give more info on the BSC and the blower and for everyone's comment:


BSC
Model: SG603TXCE
Serial Number :84326
Voltage : 230
Total Amperes : 11.3


Exhaust Blower
Name: Portable Ventilation
Type: JPV -300; Made in Taiwan
Static : 40/50 mm/aq
Power: 550watts
Speed : 2,900/3,320 rpm
Capacity :60/70 mm c.m.m
HZ : 50/60
Voltage:220 to 230v

The distance of the blower from the BSC would be about 2meters; there is a
low ceiling in that building so that the size of the duct is about 150mm x
600mm. I didn't have the chance to see the bend but you can see from the
pictures that there will be about 2 bends: first the duct that connects to
the BSC and the 2nd would be where the duct connects to the blower.

If you will look closely at the picture the duct is narrow compared to the
opening to the blower, (am not sure if I described it correctly).

Again thanks so much for the help and for connecting me to Baker.

Best regards,
Grace

-----Original Message-----
From: GHDonline (Paul A. Jensen, PhD, PE, CIH) [mailto ...

Hi Dr. Paul J.,

Just to give more info on the BSC and the blower and for everyone's comment:


BSC
Model: SG603TXCE
Serial Number :84326
Voltage : 230
Total Amperes : 11.3


Exhaust Blower
Name: Portable Ventilation
Type: JPV -300; Made in Taiwan
Static : 40/50 mm/aq
Power: 550watts
Speed : 2,900/3,320 rpm
Capacity :60/70 mm c.m.m
HZ : 50/60
Voltage:220 to 230v

The distance of the blower from the BSC would be about 2meters; there is a
low ceiling in that building so that the size of the duct is about 150mm x
600mm. I didn't have the chance to see the bend but you can see from the
pictures that there will be about 2 bends: first the duct that connects to
the BSC and the 2nd would be where the duct connects to the blower.

If you will look closely at the picture the duct is narrow compared to the
opening to the blower, (am not sure if I described it correctly).

Again thanks so much for the help and for connecting me to Baker.

Best regards,
Grace

-----Original Message-----
From: GHDonline (Paul A. Jensen, PhD, PE, CIH) [mailto:]
Sent: Sunday, September 28, 2008 12:31 AM
To: Grace Egos, , RMT, MSPH
Subject: [TB Infection Control] Re: [TB Infection Control] issues on
defective biosafety cabinet

Dear Grace:

I concur with Dr First. I have seen "reverse flow" many times . . . And in
EVERY case, either the exhaust/roof blower was under-sized or the
exhaust/roof blower was simply not operational! There are generally two
alarms on BSC Class II B2s . . . One for the supply and one for the
exhaust. Not sure which Baker model you have or which alarm(s) sounded!

Regards,

Paul J

--------------------------
Sent from my BlackBerry . . . Please excuse my fumbling thumbs!


----- Original Message -----
From: GHDonline (Grace Egos) <>
To: Jensen, Paul A. (CDC/CCID/NCHHSTP)
Sent: Tue Sep 23 23:11:19 2008
Subject: Re: [TB Infection Control] issues on defective biosafety cabinet

Reply to: issues on defective biosafety cabinet

Dear Dr. First,

Thank you very much for the prompt reply. Just a few more information:
These
are Type2B2 cabinets and are 1 year old. We had it certified and found the
flow to be reversed. I went again with an engineer where we tried
adjusting
as was demonstrated to me at the Maine. What is ironic is that the alarm
stops everytime a complete reverse flow is achieved meaning the air is
going
out.

I further inquired about the exhaust blower if whether this was supplied
also by the Baker company and they informed me these blowers were procured
separately.

I checked online the courses they are offering and is looking for one
which
they mentioned they will be conducting in Asia (Indonesia I guess?) but it
is not mentioned there. Would appreciate if you could help us with more
information and if they could atleast accommodate 1 engineer in this
course
because we could not use the cabinets at the moment and we could not
proceed
with the intended plan to operate as part the expansion plan for the MDRTB
program in the southern region of the Philippines where we are supposed to
do drug susceptibility testing.

Thank you very much for your kind accommodation to my queries.

Best regards,
Grace


Grace E. Egos, RMT, MSPH
Laboratory Manager
Tropical Disease Foundation,Inc.
Philippine International Center for Tuberculosis
Amorsolo cor. Urban Avenue
Legaspi Village, Makati City 1229
tel: 632-8102874
telefax:632-8936066
mobile: 639178506842
email: ;

-----Original Message-----
From: GHDonline (Melvin First, ScD, CIH, PE) [mailto:]
Sent: Wednesday, September 24, 2008 12:41 AM
To: Grace Egos
Subject: Re: [TB Infection Control] issues on defective biosafety cabinet

Reply to: issues on defective biosafety cabinet

You didn't identify the cabinets completely, but if they are class II,
Type
B2 I would venture a guess that the trouble is the roof fans are not
running; this results in the cabinet fan having no place to discharge its
air except through the work opening. The roof blowers may have lost the
belts driving the fan or the belts have become too loose. If that is not
the cause of roof fan failure it will be necessary to investigate the
electrical connections. When Class II, Type A cabinets have been
hard-ducted to a roof exhaust fan (although this arrangement is not
authorized) the same difficulty may manifest itself by outflow from the
work opening.

The Baker Co. of Sanford, Maine can be accessed on the web for information
on the location of their representatives and their course schedule and
locations.

I hope this information is helpful; if I can provide additional
information
please let me know.

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/

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See also:
http://www.ghdonline.org/ic/discussion/issues-on-defective-biosafety-cabinet
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See also:
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ective-biosaf/

Dear Grace:

I spoke with Cindy from The Baker Company (www.bakerco.com) and I also found the specifications for the JPV-300 blower on the web (http://www.allproducts.com/machine/jouning/61-jpv200ss.html) . . . The maximum flow rate of the JPV-300 is 60 m3/min (2,100 cfm) at 40 mm w.g. (1.6 in w.g.). The BSC requires 15.4-16.0 m3/min (543-566 cfm) at 51-64 mm w.g. (2.0-2.5 in w.g.). The Baker’s round exhaust duct is 25.4 cm (10 in) in diameter. So, the area of the round duct is 508 cm2 (78.5 in2) and the area of the rectangular duct is 900 cm2 (139 in2).

So, here are my thoughts:
1. The initial duct size is OK, but not ideal.
2. The JPV-300 is a weak fan/blower and cannot handle the pressure loss of a well-designed system. With the duct transitions and elbow, there will be even greater losses. Hence, this fan does not pull enough air. The way to check this is to drill a hole in the duct, stick your velocity meter into the center of the duct, calculate the flow rate. I suspect ...

Dear Grace:

I spoke with Cindy from The Baker Company (www.bakerco.com) and I also found the specifications for the JPV-300 blower on the web (http://www.allproducts.com/machine/jouning/61-jpv200ss.html) . . . The maximum flow rate of the JPV-300 is 60 m3/min (2,100 cfm) at 40 mm w.g. (1.6 in w.g.). The BSC requires 15.4-16.0 m3/min (543-566 cfm) at 51-64 mm w.g. (2.0-2.5 in w.g.). The Baker’s round exhaust duct is 25.4 cm (10 in) in diameter. So, the area of the round duct is 508 cm2 (78.5 in2) and the area of the rectangular duct is 900 cm2 (139 in2).

So, here are my thoughts:
1. The initial duct size is OK, but not ideal.
2. The JPV-300 is a weak fan/blower and cannot handle the pressure loss of a well-designed system. With the duct transitions and elbow, there will be even greater losses. Hence, this fan does not pull enough air. The way to check this is to drill a hole in the duct, stick your velocity meter into the center of the duct, calculate the flow rate. I suspect it will be less than 15.4-16.0 m3/min (543-566 cfm).
3. There is also the chance that the fan/blower was hooked up backwards. I suspect this was NOT done as you would have not noticed the cloth at the outlet of the fan/blower moving outward.
4. Replace the JPV-300 with a stronger fan/blower. Also note that the flow rate has a narrow range; hence you will need to have a means to adjust the exhaust flow rate! Not too much, not too little!!!

With the existing ducting system (and associated pressure losses) connected to the Class II B2 BSC with a pressure drop across the filters of 51-64 mm w.g. (2.0-2.5 in w.g.) (the lower value for a clean HEPA and the upper value for a dirty HEPA filter), the airflow rate should be 15.4-16.0 m3/min (543-566 cfm) . . . No more . . . No less . . .

This is a difficult specification to meet. So, you have the option of purchasing a Baker fan/blower or finding someone who can meet these specifications. One solution that I have seen in the US is the use of a fan/blower with a Phoenix controller in line. The fan/blower should provide the desired flow rate (plus 10-20%) at the maximum pressure drop. The Phoenix controller (8” model) would be programmed to maintain a constant flow rate (within the design range of the BSC). Yes, this will cost a bit; however, it is necessary to make certain that the airflow is correct! That’s why my personal preference is a Class II A2 BSC which recirculated into the laboratory, with regular testing & certification! Yes, there will still need to be appropriate ventilation (negative pressure) in the laboratory.

Regards,
Paul J