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Fume Hoods _ Safety Performance

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					Fume Hood Containment
          &
  Safety Performance
Standard Fume Hood
Why we use fume hood?




                        • To contain fumes and
                          hazardous chemicals


                        • Ensure Safety of laboratory
                          workers
Face Velocity vs Containment Efficiency




                                          • Fume hood meets face velocity
                                            specification but are not safe.

                                          • 30-50% of fume hoods meeting
                                            face velocity requirements fail
                                            tracer gas test.
                                            (source: www.safelab.com)
Existing Standards




●   BS 7258 (United Kingdom, Hong Kong)

●   DIN 12 924 (Germany)

●   EN 14175 (European Union)

●   ANSI/ASHRAE 110-1995 (United States)

●   NF-X-15-203 (France)

●   AS/NZS 8:2006(Australia & New Zealand)
EN 14175 : 2003




                  European Standard
                  EN 14175 : 2003
EN 14175 : 2003




• Group Effort of 11 European Countries
• Combination of BS and DIN standards
• 6 parts:
  - Part 1: Vocabulary
  - Part 2: Safety and performance requirements
  - Part 3: Type test methods
  - Part 4: On-site test methods
  - Part 5: Recommendations for installation and
  maintenance
  - Part 6: Variable air volume fume cupboards
EN 14175 : 2003


Air Flow Test

                                               0
                                              10


                                               5
                                              10
                                                    0
                                                   50

                                               5
                                              10


                                               0
                                              10



   0
  10          0
             37        37
                        0            0
                                    37    0
                                         10
                  Probe positions
EN 14175 : 2003



Inner Containment Test


                     0
                     10

                     0
                     10
                               a j t
                                s eo
                               G Ec r


              0 0
               0 0
              1 1         5
                          10

    a f l r e rag e
     n d o r e n
    Mio/P bA n mt
EN 14175 : 2003



Inner Containment Test
EN 14175 : 2003



Inner Containment Test
EN 14175 : 2003


Outer Containment Test

 ah
ss



                                                               5
                                                              60




                                                         5
                                                         20

                                                    0
                                                    10


  0
 20
                   0
                  10    6
                       40           6
                                    40          0
                                               10

       oi o i o e t q i e o u
         t n           p n    e e ue e l e
                                 a     n a
      Ps i n g fTs Eu m tf rOt rM s r m tp n
EN 14175 : 2003


Outer Containment Test
    EN 14175 : 2003



    Robustness of Containment
●    Dynamic Testing: 'Robustness' of Containment Test

●    Test equipment as per outer containment test equipment


●    Flat rectangular plate of 1.9 x 0.4m of thickness 20mm shall be
     mounted in front of cupboard.
EN 14175 : 2003


Robustness Test of Containment
ANSI/ASHRAE 110-1995




                       US Standard
        ANSI/ASHRAE 110-1995
    ANSI/ASHRAE 110-1995




    Introduction

●     Method of Testing Performance of Laboratory Fume Hoods.
●     ASHRAE: American Heating, Refrigerating and Air-Conditioning
      Engineers, Incorporation.
●     “Laboratory Fume Hoods, a Performance Test”, K.J. Caplan
      and G.W. Kruston, RP-70, ASHRAE Transactions, 1978.
●     First ASHRAE Standard is published on 1985.
ANSI/ASHRAE 110-1995




 Test Method
• Cross draft & face velocity test

• Smoke visualization test

• Tracer gas containment test
ANSI/ASHRAE 110-1995


Cross Draft & Face Velocity
• Cross draft transducer
• Accuracy: ± 3% of reading




                              • Face velocity transducer
                              • Accuracy: ± 2% of reading
ANSI/ASHRAE 110-1995


 Cross draft measurement
• Cross draft shall be less than 0.15m/s




                                           H

            ½H



                          5 feet
ANSI/ASHRAE 110-1995


Face velocity measurement
• 100% sash opening
• Face velocity shall be 0.50m/s ± 20%

                           x




  y                                         ≤300mm




                                   ≤300mm
ANSI/ASHRAE 110-1995

• 50% Sash opening
                       x



  1/2y



                           ≤300mm

• 25% Sash opening
                       x

 1/4y


                           ≤300mm
ANSI/ASHRAE 110-1995


 Flow visualization
• Enable visual inspection of fume hood air flow patterns.

• Consist 2 parts:
   – Low volume smoke test
   – High volume smoke challenge
       Grading                      Observations
        Good     No reverse flow.
                 Active flow stream into hood around boundary.
         Fair    Some reverse flow, not necessarily at the opening.
                 No visible escape.
        Poor     Reverse flow near opening.
                 Lazy flow into opening along boundary.
                 Observe potential of smoke escape.
         Fail    Smoke observed escaped from hood.
ANSI/ASHRAE 110-1995



         Low Volume Smoke Test
ANSI/ASHRAE 110-1995



   High Volume Smoke Challenge
ANSI/ASHRAE 110-1995


     Tracer Gas Containment Test
ANSI/ASHRAE 110-1995




   SF6 Gas
• Much heavier than air
• Non-flammable, non-toxic




                               Tracer gas detector
                             • To detect and capture
                               leakage of SF6 from hood.
                             • Detection limit: 0.01 PPM
ANSI/ASHRAE 110-1995




   Mannequin
• Mannequin height 1.70m,
  wearing laboratory cloth.
• Tracer gas detector placed
  near the mannequin's
  breathing zone.
ANSI/ASHRAE 110-1995


Static test
                       • Tracer gas ejector is placed at
                         150mm behind the sash.
                       • Mannequin placed 75mm in
                         front of sash.
                       • Mannequin position will
                         change according to the
                         ejector location.
                       • SF6 gas release rate is 4LPM.
                       • Data acquisition to record
                         detector reading for 5 mins.
ANSI/ASHRAE 110-1995



 Static test
• Test is conducted at 100%,
  50% and 25% sash opening.


• Every test is carried out with
  ejector in 3 positions:
   – Center
   – 300mm from the left
   – 300mm from the right

• Spillage shall not exceed
  0.1ppm, in all test positions.
ANSI/ASHRAE 110-1995


Face Hood Surface Scan
                       • To observe leakage point of the
                         hood opening.

                       • Tracer gas probe is held 1 inch
                         away from the edge of sash
                         opening, and move along the
                         edge with a speed of 3 inch per
                         second.

                       • Spillage shall not exceed
                         0.1ppm, in all test positions.
ANSI/ASHRAE 110-1995



Sash Movement Effect
• To test the effect on containment when opening or closing
  the sash.

• Sash is moved at a smooth motion between 0.3 – 0.5m/s.

• Sash movement: Closed → Full opening → Closed, repeat
  3 times.

• Conducted with ejector Located in 3 positions:
   – Center
   – 300mm from the left
   – 300mm From the right
ESCO Fume Hood


Increased Severity Challenges
• Face velocity in 0.50m/s, 0.40m/s, 0.30m/s to test the hood
  performance.

• FFU to create cross draft.
ESCO Fume Hood


Increased Severity Challenges
• Moving vertical board to pretend door open or close.
  ESCO Fume Hood



   ASHRAE Test Result for EFD-4
 • Face velocity:
    – Sash 100% open: 0.50 m/s
    – Sash 50% open: 0.83 m/s
    – Sash 25% open: 1.15m/s

 • Smoke visualization:
                                    0.50m/s        0.40m/s         0.30m/s
           Method             Normal WCD WDO Normal WCD WDO Normal WCD WDO
Low volume smoke visualization Good Good Good Good   Fair Good Good Fair   Good
High volume smoke challenge    Good Good Good Good Good Good Good Fair     Good

                                ASHRAE 110 test                     WCD: With cross draft
                                Increased severity challenge test   WDO:With door open/close
ESCO Fume Hood


ASHRAE Test Result for EFD-4



  • Static test
  Ejector position Sash open       0.5m/s         0.4m/s        0.3m/s
                     100%    Normal WCD WDO Normal WCD WDO Normal WCD WDO
        P1            50%      0      0   0   0      0   0   0     0   0
                      25%      0      0   0   0      0   0   0     0   0
                     100%      0      0   0   0      0   0   0     0   0
        P2            50%      0      0   0   0      0   0   0     0   0
                      25%      0      0   0   0      0   0   0     0   0
                     100%      0      0   0   0      0   0   0     0   0
        P3            50%      0      0   0   0      0   0   0     0   0
                      25%      0      0   0   0      0   0   0     0   0
ESCO Fume Hood


 ASHRAE Test Result for EFD-4
• Face hood surface scan
  Sash open          0.5m/s         0.4m/s         0.3m/s
              Normal WCD WDO Normal WCD WDO Normal WCD WDO
    100%        0       0   0  0       0   0  0     0.03  0
     50%        0       0   0  0       0   0  0     0.04  0


• Sash movement effect
     Sash open              0.5m/s         0.4m/s         0.3m/s
                     Normal WCD WDO Normal WCD WDO Normal WCD WDO
   Close- max- close   0       0   0  0       0   0  0     0.03  0
Safety Essentials




                     Safety
                    Essential
Safety Essentials


Fume Hood Location
Safety Essentials



Fume Hood Location
Safety Essentials



Work Safety


                    • Fume hood is not a storage!
                    • Always keep fume hood
                      clean and clear.
                    • Action must be taken
                      immediately if spillage
                      happen.
Safety Essentials


Work Safety
• Raise bulky equipment 1-2 inch off the work surface.
• Place bulky equipment towards the rear of hood and away
  from the side walls.
Safety Essentials



Work Safety
• Keep sash as low as possible when conducting experiment.
• Do not block the airfoil.
• Reduce pedestrian traffic in front of the hood
• Minimize rapid movement in front of hood.
• Always keep laboratory windows and doors closed.
Safety Essentials



 Work Safety
• Do not use a hood for any function for which it was not intended.
• Certain chemicals or reactions require specially constructed
  hoods.
   – Perchloric acid hoods shall be made of stainless steel and
      equipped with a wash down system.
   – Polycarbonate sash shall be applied when using hydrofluoric
      acid.
   – Work involving harmful micro-organisms should be done in a
      biosafety cabinet, rather than a chemical fume hood.
• Close the sash when finished hood work or leaving experiments
  or chemicals unattended.
End




      Thank you!

				
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