Calculate Lighting Fixture’s Beam Angle


ScreenHunter_01 Feb. 19 20.59

  • Calculate Lighting Fixture Beam Angle
  • Calculate Illumination at Surface from Beam Angle.
  • Calculate Lighting Fixture Lumen from Beam Angle.
  • Calculate Illuminated Diameter from Beam Angle.

FREE DOWNLOAD

Advertisements

Calculate Size of Neutral Earthing Transformer (NET)


Calculate Size of Neutral Earthing Transformer (NET) having following details

 Main Transformer Detail :

  • Primary Voltage(PVL): 33KV
  • Secondary Voltage (SVL): 11 KV
  • Frequency(f)=50Hz
  • Transformer Capacitance / Phase(c1)=0.006 µ Farad
  • Transformer Cable Capacitance / Phase(c2)= 0003 µ Farad
  • Surge Arrestor Capacitance / Phase(c3)=0.25 µ Farad
  • Other Capacitance / Phase(c4)=0 µ Farad

Required for Neutral Earthing Transformer:

  • Primary Voltage of the Grounding Transformer (Vp) =11KV
  • Secondary Voltage of the Grounding Transformer (Vs) =240V
  • Neutral Earthing Transformer % Reactance (X%)=40%
  • % of Force field condition for Neutral Earthing Transformer (ff) =30%
  • Neutral Earthing Transformer overloading factor(Of)=2.6
  • Neutral Earthing Transformer Base KV (Bv) =240V=0.240KV

Calculation:

  • Phase to Neutral Voltage (Vp1) =SVL /1.732
  • Phase to Neutral Voltage (Vp1) =11 /1.732 = 6.35 KV
  • Phase to Neutral Voltage under Force Field Condition (Vf) =Vp + (Vpxff)
  • Phase to Neutral Voltage under Force Field Condition (Vf)=6.35+ (6.35×30%) =8.26KV
  • Total Zero Sequence Capacitance (C)=C1+C2+C3+C4
  • Total Zero Sequence Capacitance (C)=0.006+0.0003+0.25+0=0.47730 µ Farad
  • Total Zero Sequence Capacitance Reactance to Ground (Xc)=10×6 / (2×3.14xfxC)
  • Total Zero Sequence Capacitance Reactance to Ground (Xc)=10×6 / (2×3.14x50x0.47730)=6672.35 Ω/Phase
  • Capacitive charging current/phase (Ic)=Vf / Xc
  • Capacitive charging current/phase (Ic)=8.26×1000 / 6672.35 = 1.24Amp
  • Total Capacitive charging current (It) =3xIc
  • Total Capacitive charging current (It) =3xIc =3×1.24 =3.71Amp
  • Rating of Neutral Earthing Transformer (Pr)=VpxIt
  • Rating of Neutral Earthing Transformer (Pr)=11×3.71=40.83KVA
  • Size of Neutral Earthing Transformer (P)=Pr/ Of
  • Size of Neutral Earthing Transformer (P)=40.83/ 2.6 = 16KVA
  • Residual Capacitive reactance (Xct) =Xc/3
  • l Capacitive reactance (Xct) = 6672.35 /3 =2224.12Ω
  • Turns Ratio of the Grounding Transformer (N)= Vp/Vs =11000/240 =45.83
  • Required Grounding Resistor value at Secondary side (Rsec)=Xct/NxN
  • Required Grounding Resistor value at Secondary side (Rsec)=2224.12 /45.83×45.83 =1.059 Ω
  • Required Grounding Resistor value at primary side (Rp)=Xct
  • Grounding Resistor value at primary side (Rp)= 2224.12Ω
  • Neutral Earthing Transformer Secondary Current=P/Vs
  • Neutral Earthing Transformer Secondary Current=16000/230= 65.44Amp
  • Neutral Earthing Transformer Secondary Resistor Current (for 30 Sec)=1.3xItxN
  • Neutral Earthing Transformer Secondary Resistor Current (for 30 Sec)=1.3×3.71×45.83=221.18Amp
  • Neutral Earthing Transformer Reactance Base(Base X)=BvxBv/P/1000
  • Neutral Earthing Transformer Reactance Base(Base X)=0.24×0.24/11/1000=3.67Ω
  • Neutral Earthing Transformer Reactance in PU (Xpu)=X% =40%=0.04Pu
  • Neutral Earthing Transformer Reactance (X)=Xpu x BaseX
  • Neutral Earthing Transformer Reactance (X)=0.04×3.67 =0.15Ω
  • Neutral Earthing Transformer X/R Ratio=X/Rsec
  • Neutral Earthing Transformer X/R Ratio=0.15/1.059 = 0.14
  • Fault current through Neutral (single line to ground fault) (If)=Vp1/Rp
  • Fault current through Neutral (single line to ground fault) (If)=6.35×1000/2224.12 =2.86Amp
  • Short time Rating of Neutral Earthing Transformer=PxOf =16×2.6 =41KVA

Result:

  • Rating of Neutral Earthing Transformer (P)=40.83/ 2.6 = 16KVA
  • Short time Rating of Neutral Earthing Transformer=41KVA
  • Ratio of Neutral Earthing Transformer =11000/240 Volt
  • Neutral Earthing Transformer Secondary Current=65.44A
  • Required Grounding Resistor value at primary side (Rp)=2224.12Ω
  • Required Resistance at secondary side (Rsec)= 1.059Ω
  • Neutral Earthing Transformer Secondary Resistor Current (for 30 Sec)= 221.2A

Calculate Required Air ventilation and Heat generation of D.G Set


Heat Generated by Generator:

  • For generator set installations, the heat radiated by the generator can be estimated by
  • H (kW) =P X ((1/Eff)-1)
  • H (Btu/min) =P X ((1/EFF)-1) x56.9
  • Where:
  • H = Heat Radiated by the Generator (kW), (Btu/min)
  • P = Generator Output at Maximum Engine Rating (kW)
  • Eff = Generator Efficiency % / 100%
  • Example: 975 kW standby generator set has a generator efficiency of 92%. The generator radiant heat for this genset can be calculated as follows.
  • P = 975 kW
  • Efficiency = 92% = 0.92
  • H = 975 x ((1/92%) – 1)
  • H= 84.78 kW
  • H = 975 x ((1/92%) – 1) x 56.9
  • H = 4824 Btu/min

 Types of Ventilation System:

  • Type:1 (Preferred Design) (Routing Factor of 1)
  • Outside air is brought into the engine room through a system of ducts. These ducts should be routed between engines, at floor level, and discharge air near the bottom of the engine and generator. .
  • Ventilation air exhaust fans should be mounted or ducted at the highest point in the engine room. They should be directly over heat sources. This system provides the best ventilation with the least amount of air required.
  • Type 2 (Skid Design) (Routing Factor of 1)
  • Outside air into the engine room through a system of ducts and routes it between engines.
  • Type 2, however, directs airflow under the engine and generator so the air is discharged upward at the engines
  • The most economical method to achieve this design is to use a service platform. The platform is built up around the engines and serves as the top of the duct
  • Ventilation air exhaust fans should be mounted or ducted at the highest point in the engine room. They should be directly over heat sources.
  • This system provides the best ventilation with the least amount of air required.
  • Type 3 (Alternate Design) (Routing Factor of 1.5)
  • If Ventilation Type 1or Type 2 is not feasible, an alternative is Type 3; however, this routing configuration will require approximately 50% more airflow than Type 1.
  • Outside air is brought into the engine room utilizing fans or large intake ducts. The inlet is placed as far away as practical from heat sources and discharged into the engine room as low as possible. The air them flows across the engine room
  • Ventilation air exhaust fans should be mounted or ducted at the highest point in the engine room. Preferably, they should be directly over heat sources
  • Type 4 (Less Effective Design) (Routing Factor of 2.5)
  • If Ventilation Type 1, Type 2 and Type 3 are not feasible, then Type-4 method can be used; however, it provides the least efficient ventilation and requires approximately two and a half times the airflow of Ventilation Type 1
  • Outside air is brought into the engine room using supply fans, and discharged toward the turbocharger air inlets on the engines.
  • Ventilation exhaust fans should be mounted or duct from the corners of the engine room
  • This system mixes the hottest air in the engine room with the incoming cool air, raising the temperature of all air in the engine room.
  • It also interferes with the natural convection flow of hot air rising to exhaust fans.
  • Engine rooms can be ventilated this way, but it requires extra large capacity ventilating fans.

Ventilation for Generator:

  •  When Generator set installations in Room proper ventilation is required for Generator set.
  • A properly designed engine room ventilation system will maintain engine room air temperatures within 8.5 to 12.5°C (15 to 22.5°F) above the ambient air temperature.
  • For example, If the engine room temperature is 24°C (75°F) without the engine running, the ventilation system should maintain the room temperature between 32.5°C (90°F) and 36.5°C (97.5°F) while the engine is in operation.
  • Ensures engine room temperature does not exceed 49°C (120°F).
  • Required Ventilating Air is calculated as
  • V=((H / D x Cp x T)+ Combustion Air) X F
  • Where:
  • V = Ventilating Air (m3/min), (cfm)
  • H = Heat Radiation i.e. engine, generator, aux (kW),(Btu/min)
  • D = Density of Air at air temperature 38°C (100°F). The density is 1.099 kg/m3 (0.071 lb/ft3)
  • CP = Specific Heat of Air (0.017 kW x min/kg x °C),(0.24 Btu/LBS/°F)
  • T = Permissible temperature rise in engine room (°C), (°F)
  • F = Routing factor based on the ventilation type
  • Example: The engine room for generator set has a Type 1 ventilation routing configuration and a dedicated duct for combustion air. It has a heat rejection value of 659 kW (37,478 Btu/min) and a permissible rise in engine room temperature of 11°C (20°F).
  • V=((659 / 1.0099X0.017X11)+ 0)X1
  • V = 3206.61 m3/min
  • V=((659 / 0.071 X 0.024 X 20)+ 0)X1
  • V = 109970.7 cfm

Thumb Rule-12 (Quick Reference of DG Set)


 

Standard Size of The DG sets

KVA KVA KVA KVA KVA
7.5 KVA 20KVA 35 KVA 62.5 KVA 100 KVA
10 KVA 25 KVA 40 KVA 75 KVA 125 KVA
15 KVA 30 KVA 50 KVA 82.5 KVA 200 KVA

 

D.G Foundation Bar Size

Rating of D.G set Size of Bar
Up to 82.5 KVA 10MM
100 KVA To 200 KVA 12MM
250 KVA to 500KVA 16MM

 

Minimum Capacity of  Fuel Service Tank

AS per CPWD
Capacity of DG set Minimum Fuel Tank Capacity
Upto 25 KVA 100 Liters
Above 25 to 62.5 KVA 120 Liters
Above 62.5 KVA to 125 KVA 225 Liters
Above 125 KVA to 200 KVA 285 Liters
Above 200 KVA to 380 KVA 500 Liters
Above 380 KVA to 500 KVA 700 Liters
Above 500 KVA to 750 KVA 900 Liters

 

Battery Size for D.G Set

                                                           AS per CPWD

DG Set Capacity Battery Capacity (AH) Cu Cable Size (Sq. mm) Electrical System (Volts)

Up to 25 KVA

88 35

12

Above 25 KVA upto 62.5 KVA

120 50

12

Above 62.5 KVA up to 82.5 KVA

150 50

12

Above 82.5.KVA up to 125 KVA

180 50

12

Above 125 KVA up to 500 KVA

180 70

12

Above 500 KVA

360 70

24

 

Depths of PCC (Plain Cement Concrete)  for DG Set

As per CPWD

DG Set Capacity (KVA) Typical Depth of PCC Foundation (For soil bearing capacity 5000 kg/sq meter)
750-2000 600 mm
625 400 mm
320-500 400 mm
200-320 400 mm
82.5 -200 400 mm
Upto 82.5 200 mm

 

Foundation & Earthing for D.G Set

As Per CPWD

Ieam Descriptions
D.G set inside Room A PCC foundation (1:2:4, M-20 grade) of approximate depth 150 mm above the finished Generator set Room Floor level
The  length  and  breadth  of  foundation  should  be  at  least  250  mm   more on all sides than the size of the enclosure.
D.G set in Open Room A PCC (1:2:4, M-20 grade) foundation  of  weight  2.5  times  the  operating  weight  of  the  Generator set  with  enclosure  or  as recommended by the Generator set manufacturer, whichever is higher
300 mm of this foundation height should be above the ground level. The length and breadth of foundation should be at least 250 mm more on all sides than the size of enclosure.
Earthing Copper plate earthing (Neutral Grounding) shall be provided for DG Sets of capacity 500 KVA or above
whereas G.I. plate earthing (Neutral Grounding) shall be provided for DG Sets below 500 KVA capacity. The body earthing shall generally be of G.I
Numbers of earthing for each DG Sets 2No’s  earthing sets for Genset/ control panel body.
2No’s earthing sets for neutral.
In case there are more than one DG Set in one location, independent two nos. neutral earthing shall be provided for each DG set. However, two nos. earthing sets shall be common for the body earthing of DG Sets
DG Set of 500 KVA capacity or above:- Copper strip
DG Set below 500 KVA capacity:- GI strip

 

D.G Detail according to Size

D.G Size (KVA) L x W x H (Canopy) mm Approx Weight (Kg) Fuel Tank (Ltrs) Fuel Consumption (Ltr/hr) Oil Consumption (Ltr/hr)
12.5 2040 x 1230 x 1450 1050 60 2.3 0.02
15 2040 x 1230 x 1450 1050 65 2.3 0.02
20 2240 x 1230 x 1450 1300 65 3.7 0.03
30 2510 x 1130 x 1450 1300 65 6.3 0.03
40 3350 x 1180 x 1650 1500 100 7.8 0.03
50 3350 x 1180 x 1650 1500 100 8.3 0.03
62.5 3350 x 1180 x 1650 1930 150 10.5 0.03
75 3605 x 1405 x 1600 1950 150 13 0.03
100 3940 x 1700 x 1850 2500 300 15.7 0.05
125 3950 x 1700 x 1850 2700 300 19 0.05
140 4600 x 1850 x 1950 3580 300 22.6 0.06
160 4600 x 1850 x 1950 3720 450 25.9 0.14
180 4970 x 1730 x 2045 3870 450 27.7 0.14
200 4970 x 1730 x 2045 3950 450 29.8 0.14
250 4970 x 1730 x 2050 4660 450 37.7 0.15
275 5700 x 2030 x 2515 5860 450 50 0.15
320 5700 x 2030 x 2515 5860 450 57 0.3
400 5905 x 2030 x 2520 6180 990 65.1 0.3
500 6205 x 2030 x 2550 6990 990 81.3 0.3

 

FUEL CONSUMPTION  FOR DG SET:

Generator KVA Diesel consumption Liter per hour
5 1.25
15 2.91
20 4.78
25 4.78
30 6.55
40 8.11
50 10.19
62.5 10.92
75 13.52
82.5 13.52
125 19.76
140 23.4
200 30.99

 

D.G Spacing Guidance

Description DG set with Acoustic Enclosure Open DG set in room.
in Open Area in Closed Area
Free space on both sides Min. 1.5 m Min. 1.5 m Min. 2 m
Free space at front side (Radiator Hot air outlet at Front) Min. 3 m Min. 3 m N/A
Free space at front side (Radiator Hot air outlet at Top) Min. 1.0 m Min. 1.5 m N/A
Free space at rear side
(Alternator)
Min. 2 m Min. 2 m Min. 2 m
Fresh air inlet opening area N/A N/A Min 1.5 times of the Radiator area.
Hot air discharge opening area N/A N/A Min 2.5 times of the Radiator area.
Distance between two sets Min 1.5 meter between two
canopies
Min 1.5 meter between
two canopies
Min 1.5 meter between two foundations.

 

Simple Calculation of Flood Light, Facade Light, Street Light & Signage Light-(Part2)


(B) Facade Lighting:

  • Normally Facade Lighting are used to illuminate Building area from Outer Side. 
  • There are three factor should be consider while designing of outdoor Facade Lighting.
  1. Setback
  2. Spacing
  3. Aiming

1) Setback:

  • The recommended setback should be 3/4 times the building height. 
  • If a building is 10 Meter tall, the recommended setback is 7.5 Meter from the building. 
  • If the locating the floodlight closer to the building will sacrifice uniformity and If setting it further back will result in loss of efficiency.
  • Setback distance = 3/4 x Building height
  • Setback distance =3/4 x (10 Meter) = 7.5 Meter 

a

2) Spacing:

  • Spacing of floodlights should not be exceeding two times the setback distance. 
  • If the setback is 7.5 Meter the floodlights should not be placed more than 15 Meter apart.
  • Spacing = 2 x setback distance
  • Spacing=2 x 5  = 15 Meter

b

3) Aiming:

  • The floodlight should be aimed at least 2/3 the height of the building.
  • If a building is 10 Meter high, the recommended aiming point is approximately 6.6 Meter high. 
  • After installation aiming can be adjusted to produce the best fine appearance. 
  • Aiming Point = 2/3 x Building Height.
  • Aiming Point =2/3 (10 Meter) = 6.6 Meter high

c

(C) Sinage Lighting:

  • Normally Sinage Lighting are used to illuminate Sinage Board either Floor Mounted or Pole Mounted
  • There are three factor should be consider while designing of Sinage Board Lighting.
  1. Setback
  2. Spacing
  3. Aiming

1) Setback:

  • When using floodlights to light a sinage, the setback should be 3/4 the sign height
  • If the sinage height is 18 Meter then the setback distance would be 13.5 Meter. 
  • If the floodlight closer to sinage will sacrifice uniformity while setting it further back will in a loss of efficiency.
  • Setback distance = 3/4 x sinage height
  • Setback distance =3/4 (18 Meter) = 13.5 Meter.

d

2) Spacing:

  • The spacing floodlights should not be exceed two times the setback distance. 
  • If the setback is 13.5 Meter, the floodlights should not be placed more than 27 Meter apart. 
  • Spacing = 2 x setback distance.
  • Spacing = 2 x 5 (Meter) = 27 Meter.

e

3) Aiming:

  • The floodlight should be aimed at least 2/3 up the sign.
  • If a sign is 18 Meter tall, then the floodlight should be aimed approximately 12 Meter high. 
  • Aiming can be adjusted to produce the best appearance. 
  • Mounting a full or upper visor to the floodlight can reduce unwanted glare. 
  • Aiming point = 2/3 x sign height
  • Aiming point =2/3 (18 Meter) = 12 Meter high

f

Street Light Pole Height & Spacing (as per CPWD):

  • There are four type of Street Light Pole arrangement.
  • One side Type.
  • Staggered Type.
  • Opposite Type.
  • Central Type.
  • As per CPWD we can calculate Pole Height and Spacing as per under

(1) One side Street Light Pole arrangement.

  • Pole Height = Width of Road.
  • Pole Spacing = 3 to 4 Times Height of Pole.
  • If the Road width is 8 Meter than
  • Pole Height=8 Meter
  • Pole Spacing =24 to 32 Meter.

g

(2) Staggered Type Street Light Pole arrangement.

  • Pole Height = 0.8 time Width of Road.
  • Pole Spacing = 3 to 4 Times Height of Pole.
  • If the Road width is 8 Meter than
  • Pole Height=6.4 Meter
  • Pole Spacing =24 to 32 Meter.

h

(3) Opposite side Street Light Pole arrangement.

  • Pole Height = 0.5 time Width of Road.
  • Pole Spacing = 3 to 4 Times Height of Pole.
  • If the Road width is 8 Meter than
  • Pole Height=6.4 Meter
  • Pole Spacing =24 to 32 Meter.

(4) Central Street Light Pole arrangement.

  • Pole Height = 0.8 time Width of Road.
  • Pole Spacing = 3 to 4 Times Height of Pole.
  • If the Road width is 8 Meter than
  • Pole Height=4 Meter
  • Pole Spacing =24 to 32 Meter.

Simple Calculation of Flood Light, Facade Light, Street Light & Signage Light-(Part1)


Introduction:

  • Outdoor Lighting can be classified according to the location where it can be installed or its function which use for highlight landscape area.
  • Outdoor Lighting can be classified as
  1. Flood Lighting,
  2. Facade Lighting and
  3. Signage Lighting
  4. Street Light

(A) General Outdoor Flood Lighting:

  • Normally Pole mounted floodlights are used to illuminate general lighting area of parking lots and storage yards. 
  • There are three factor should be consider while designing of outdoor flood lighting.
  1. Mounting Height.
  2. Spacing
  3. Aiming Distance.
  4. Horizontal Aiming.

1) Mounting Height:

  • Mounting height should be one half the distance across the area to be lighted.
  • If the area to be lighted is 16 Meter, the lowest recommended mounting height is 8 Meter. 
  • Mounting height = 1/2 distance to be lighted
  • 1/2 (16 Meter.) = 8 Meter. 

1

2) Spacing:

  • When more than one Luminar / pole is required than distance between two adjacent luminar / Pole is 4 times Mounting height of luminar /pole.
  • If the mounting height of luminar /Pole is 8 Meter than distance between adjacent Luminar is 32 Meter.
  • Pole Spacing = 4 x mounting height.
  • 4 (8 Meter pole) = 32 Meter between poles

2

3) Vertical Aiming:

  • The fixture should be aimed 2/3 of the distance across the area to be lighted and at least 30 degrees below horizontal. 
  • If the area to be lighted is 16 Meter across, the recommended aiming point is 10.6 Meter.
  • Aiming point = 2/3 Distance to be lighted.
  • 2/3 (16 Meter) = 10.6 Meter aiming point
  • To minimize glare, the recommended aiming point distance should never exceed twice the mounting height.
  • If a pole is 8 Meter high, the vertical aiming point should not exceed 16 Meter.  
  • 2 (8 Meter mounting height) = 16 Meter. 

3

4) Horizontal Aiming:

  • When two floodlights is mounted to a single pole then horizontal aiming also must be considered.
  • Each floodlight should be vertically aimed according to the two-thirds rule. 
  • The floodlights should be aimed up to 90 degrees apart. 

4

Calculate Size of Ventilation Fan


  • Calculate Size of Ventilation Fan for Bathroom of 10 Foot Long,15 Foot width and 10 foot height .

Calculation:

  • Area of the Room=Length x Width x Height
  • Area of the Room=10 x 15 x 10 =1500 Cub. Foot
  • From the table Air Changing Rate (ACH) for Bathroom = 8 Times/Hour.
  • Size of Ventilation Fan = (Area of Room x ACH ) / 60
  • Size of Ventilation Fan = (1500 x 8 ) / 60 = 200 CFM
  • Size of Ventilation Fan = 200 CFM

 

Recommended Air Change Rates For  Room  (ACH)
Type of Room Air Change Rate /Hour Consider
Shower Area 15 To 20 20
Bathroom & Shower Rooms 15 To 20 15
Bathroom 6 To 10 8
Bedrooms 2 To 4 4
Halls & Landings 4 To 6 5
Kitchens 10 To 20 15
Living & Other Domestic Rooms 4 To 6 5
Toilets – Domestic 6 To 10 8
Utility Rooms 15 To 20 15
Cafés 10 To 15 15
Canteens 8 To 12 10
Cellars 3 To 10 6
Changing Rooms with Showers 15 To 20 15
Conference Rooms 8 To 12 8
Garages 6 To 10 8
Hairdressing Salons 10 To 15 13
Hospital Wards 6 To 8 7
Laundries & Launderettes 10 To 15 13
Meeting Rooms 6 To 12 7
Offices 4 To 6 6
Restaurants & Bars 10 To 15 12
School Rooms 5 To 7 6
Shops 8 To 10 9
Sports Facilities 4 To 6 6
Store Rooms 3 To 6 5
Workshops 6 To 10 8
Assembly rooms 4 To 8 8
Bakeries 20 To 30 25
Banks/Building Societies 4 To 8 5
Billiard Rooms * 6 To 8 5
Boiler Rooms 15 To 30 25
Canteens 8 To 12 10
Changing Rooms Main area 6 To 10 8
Changing Rooms Shower area 15 To 20 17
Churches 1 To 3 3
Cinemas and theatres * 10 To 15 12
Club rooms 0.12 0.12
Compressor rooms 10 To 15 15
Conference rooms 8 To 12 12
Dairies 8 To 10 10
Dance halls 0.12 0.12
Dental surgeries 12 To 15 15
Dye works 20 – 30 30
Electroplating shops 10 To 12  
Engine rooms 15 To 30 30
Entrance halls & corridors 3 To 5 5
Factories and workshops 8 To 10 10
Foundries 15 To 30 20
Glasshouses 25 To 60 50
Gymnasiums 0.6 0.6
Hospitals – Sterilizing 15 To 25 20
Kitchens – Domestic 15 To 20 15
Kitchens – Commercial 0.3 0.3
Laboratories 6 To 15 12
Lavatories 6 To 15 12
Lecture theatres 5 To 8 8
Libraries 3 To 5 4
Mushroom houses 6 To 10 8
Paint shops (not cellulose) 10 To 20 15
Photo & X-ray darkrooms 10 To 15 12
Public house bars 0.12 0.12
Recording control rooms 15 To 25 20
Recording studios 10 To 12 10
Shops and supermarkets 8 To 15 12
Squash courts 0.04 0.04
Swimming baths 10 To 15 12
Welding shops 15 To 30 20
 
 
%d bloggers like this: