P601 Examination & Testing of LEV - Oxyl8 · 2017-05-08 · 17 How often should force-fed...

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P601 Examination & Testing

of LEV

Practice

Written Theory

Exam Questions

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Presenter: Bill Cassells BSc MPhil DSH CEng CMIOSH FIPlantE FRSH FSOE RSP

2017 v10.4


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Professional Development in LEV

1 What is the normal periodicity required by CoSHH Reg 9 for examining & testing LEV systems? 2 What LEV systems need to be tested monthly (be precise)? 3 What frequency should be set for examining & testing LEV on an aluminium grinding wheel

(and why)? 4 What should be the frequency of testing on an LEV system associated with an asbestos strip-

ping out project? 5 A fitter is Linishing a section of lead sheet. What should be the frequency of testing for the LEV

system? 6 What regulation in CoSHH deals with the Hierarchy of Control? 7 Name 4 important steps which must be considered under the Hierarchy of Control and give an

example for each one 8 When an employer considers a new process for the first time what is the first thing they should

do? 9 If following an audit it was found that the dust levels were significantly above the WEL – broad-

ly speaking what steps would you take? 10 Which CoSHH Regulation covers the statutory examination and testing of LEV plant?


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11 How long should RPE face seal fit test records be kept 12 A visitor comes onto site to do some contract work, discuss the responsibilities and practicalities

for completing the risk assessment required by the CoSHH Regulations? 13 If someone comes onto site and asks to inspect your CoSHH records. How should they be kept? 14 For how long should CoSHH records be kept under Reg9? 15 For how long should test records for the examination & testing of re-useable RPE be kept? 16 For how long should personal dust monitoring records be kept? 17 How often should force-fed respirators be examined/tested? 18 When should a user check his PPE/RPE 19 What is the best respirator to use in an enclosed vessel and why? 20 Explain what the Assigned Protection Factor (APF) on a respirator filter relates to? Give an ex-

ample. 21 An employer has obligations to employees under CoSHH Regs. What are the first steps they

need to consider?


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22 Under Regulation 9 – when should tight fit RPE be repeat face-seal fit tested – Give 3 exam-

ples? 23 What should an effective LEV system do? 24 Detail four methods for controlling degreasing solvent vapours from a degreasing tank? 25 If you have a choice of using LEV or breathing apparatus – Why would you choose LEV? 26 Under CoSHH Regulation 6 you’ve done a Risk Assessment – but what else is now required? 27 Why should an airflow indicator be fitted to a hood? What CoSHH Regulation ‘implies’ the fitting

of Gauges and Indicators 28 Why is general ventilation unsuitable for controlling exposures to highly toxic substances? 29A room is being used to store flammable substances. It has a trickle ventilation system provided by two fans in the wall. These fans can be set to operate in high flow if there is a spillage within the room. Are these fans LEV? Does this system require Examination & Testing under CoSHH? If so—what periodicity would be required between exams?


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30 Under what circumstances should an LEV Tester/Examiner consider putting a “Fail” sticker on a system?

31 Describe a Receptor Hood (give an example)? What are the weaknesses in Receptor Systems and where can they NOT be used (and why?)

32 Describe a Captor Hood (give an example) What is the main weakness in use of moveable Captor Hoods? 33 Describe a Partial Enclosure (give an example) What is the phenomenon which occurs at a hood with an operator in fron—and why is it an is-

sue? 34 What are the potential benefits of using partial enclosure instead of a capture hood (list at least

5)? 35 On the other hand—is there any benefit you can suggest top using a Captor Hodd instead of a

Partial Enclosure? 36 What should be the face velocity of a partial enclosure which has a process with a low toxicity

powder inside it? 37 What would be the range of face velocities for a partly enclosed cabinet being used to weigh

out solids/powders?


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38 What is the minimum recommended face velocity for a Partial Enclosure?

39 The minimum air movement necessary to overcome opposing air currents and cause contami-

nated air to flow into a hood is called what? 40 Hoods have a wide range of shapes. They fall into a number of basic types – what are they?

Give an example for each type. 41 Why would a canopy hood not be suitable for controlling contaminants from a cold process? 42 What would be the recommended Captor Velocity range for a slot extracting mist from an elec-

troplating process? 43 What would be the captor velocity range for a slot extracting vapours from an open tank? 44 How would you measure the Captor Control distance at a flexible arm welding hood? 45 What is the method used to determine the style of hood which should be chosen for a particular

operation to ensure the operator would be adequately protected? 46 Explain why you should always ensure that the “Capture Zone” encompasses the “Working

Zone”? Use a diagram to show what you mean.


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47 What does adding a flange to a plain ended duct outlet do to nthe velocity along the centreline (be specific!)?

48 What method would you use to balance flows in amulti-branch system? Explain the principles. 49 If you had a system with multiple branches to hoods but the system was designed to be capa-

ble of controlling ONLY from a limited number of those hoods at one time. What physical ar-rangement would you make to allow this to work efficiently?

50 If you were taking readings in the Index Duct what duct run are you working on? 51 What facilities should be provided in the ducting by the designer? 52 What type of fan is particularly vulnerable to stalling. What causes stalling in a fan? What

would happen to noise and vibration when a fan stalls? 53 When is the stall condition in a ventilation system likely to be found on an LEV powered by an

Axial Fan? 54 If you have an existing system with two branches to to hoods and you add in an extra duct

branch near to the fan. The fan power is increased to increase the flowrate at the fan. It is found that the noise levels have increased significantly particularly in the new duct close to the fan. What could be causing the increased noise levels?


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55 If the ducting in a multi-branch system could have chemicals or acids going down it – what type of fan would you recommend? What duct material would you use?

56 What fan would you recommend for a system carrying heavy fume loadings where the gas

cleaning system was unreliable? 57 What type of fan and fan impellor would you specify/expect in a system handling everything

from fine sawdust to wood chips where the filter is situated downstream of the fan?

58 What would be the capture velocity achieved at half a diameter from the entrance from a plain

ended round duct hood fitted with a flange? 59 Adding a flange to a duct outlet where there was only a plain ended duct befdorehand—this

would increase the velocity along the centre-line at one diameter out by approximately what percentage?

60 What is the recommended capture velocity range for welding fume? Why is there a range—

explain the reasons and give examples. 61 At commissioning - describe the most accurate method for balancing air flows in a multi

branch system? 62 A centrifugal fan has been installed incorrectly and the fan is running backwards. What would

be the effects on the performance of the system 63 In a similar situation—an Axial fan has had the 3 phase motor wired incorrectly—explain

what you would expect to see in this situation?


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64 What type of cleaning device would you use for cleaning large volumes of air with coarse saw-dust?

65 What type of dusct collector would you expect to see being used in the LEV system of a small

woodworking shop handling everything from fine dust to sawdust/small chips? 66 What sort of filtration would you use to scrub Hydrochloric Acid mist? 67 If you had a process in which large qualtities of fine exp[sloive dusts were produced—what

filtration options could you expect to find (give 2 filter type examples—with descriptions) 68 What is the minimum stransp[ort velocity required in a duct handling the following:- A Laboratory chemicals/solvents in vapour form B Electroplating mist C Cement Dust D Flour Dust E Wood shavings F Grinding dust 69 A centrifugal fan. Comment on effect on efficiency and tip speed if it has a backward inclined

impellor blade fitted? 70 What filter would you NOT use where very fine particles < 2 micron diameter were produced

from the process? What filter system WOULD you recommend? 71 What velocity would typically be expected at the entrance to an LVHV? 72 What’s the benefit of running ducting under negative pressures?


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73 Why would you put the filter upstream of the fan? 74 Why in a system that had a slide (blast gate?) damper – why would you have chosen it? 75 Describe the basic components of an LEV system that would be needed to control wood dust in

a workshop which includes a bench circular saw, a jig saw and a planer along with portable tools.

76 What would your principle concerns be if you were recirculating air from an extraction system

which had been through an air cleaner? 77 You arrive to examine and test a system which is recirculating air from a dust filter back into

the workshop. What comments would you make in your report regarding further tests which may be required on this unit?

78 Active Carbon/charcoal filters are particularly effective at filtering organic solvent vapours.

What 3 concerns might you have with a carbon filter which is being used for such a purpose and which recirculates the clean air back into the workroom?


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79 Neglecting any increased resitance losses—ie in an ideal system—what would happen to static

pressure and KW draw on the fan f there was an increase in airflow (eg frequency or rpm in-creased)?

80 Where would the observer stand when using a Dust/Tyndall Beam lamp? 81 What does the Dust Lamp show, ie what category of dust(s)?

82 If you had an enclosed spray room being used to spray 2-pack isocyanate paints – what simple

test could you use to determine if the room was under negative pressure? 83 When undertaking a statutory examination & test (TExT) on an enclosed spray room handling

isocyanate containing paints—what test must be undertaken every time? What should happen with the results of that tes?

84 At what pressure and temp is standard air at a density of approximately 1.2kg/m3? What is the

significance of Standard Conditions with respect to the instruments you use? 85 Explain what you would need to do if you were measuring duct velocities in a duct where the

gas temperatures were 800C? 86 What would you use a Tyndall Beam (Dust) lamp for? Simple question—but think carefully

about your answer! 87 During a TExT you note that the static pressure upstream of a certain point has fallen signifi-

cantly from the initial examination and test. List the possible faults?


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88 This time the Static Pressure behind the hood has decreased significantly. There are no obvious faults upstream of that point. What is the fault and what is the most likely cause?

89 Explain what would happen to the upstream Static Pressure and also the downstream Static

Pressure either side of a filter—if the bags were becoming ‘blinded’? 90 What are the reasons as to why you should not use a rain cowl or Chinese hat? Give a descrip-

tion and simple sketch of a suitable weatherproof termination. 91 What is the minimum recommended efflux velocity from a stack? 92 What is the range of (accurate) velocities which can be obtained/read using a rotating vane an-

emometer? 93 Describe the phenomenon Static Regain? Where might it occur in a ducted system? Use a

sketch to illustrate your explanation. 94 Describe the Vena Contracta and how does it arise (use a sketch)? What impact could this have

on readings in the duct behind a hood and how would you make sure you took accurate read-ings?


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95 The average face velocities measured at a partial enclosure were 0.7m/s with the highest read-ing at 1.0m/s and the lowest at 0.5m/s. Would you consider this to be acceptable and if so ex-plain why?

96 On this occasion the average face velocity was 0.46m/s and the highest reading obtained was

0.53m/s and the lowest was 0.39. What comments would you make regarding the face velocity results for this hood.

97 The Static Pressure (Sp) downstream of the fan has reduced significantly compared with the year

before. What could be causing this? 98 If there is a drop in pressure immediately after the hood – what problem(s) downstream of the

test point could be causing this? 99 You are being asked to examine and test a system which is handling a new active pharma-

ceutical drug. Which side of the fan would you take readings and why? 100 The client does not permit you to stick ‘red fail’ stickers to hood that you have examined and

found to be unsatisfactory. What other option is there?

P601 Examination & Testing of LEV - Oxyl8 · 2017-05-08 · 17 How often should force-fed...

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