education mine ventilation docs36

7/27/2019 Education Mine Ventilation Docs36

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1



2

Outline

• Airflow Measurements

– How to take air readings

– Measuring areas

– Mean Entry Velocity

• Principals of Airflow

• When and Where to take Air Measurements

• Actions for Excessive Methane



3

Three categories of Airflow

Measurements

• Low Velocity (0 to 120 fpm)• Medium Velocity (120 to 2000 fpm)

• High Velocity (>2000 fpm)



4

The principal mechanism for taking

medium air velocity measurement is the

Anemometer.

A high speed

anemometer ismost often used

for high velocity

air measurements!



5

Taking Anemometer Measurements

• Make sure to zero dial!

• Make sure air flow is into the back of the

anemometer.

• Press lever to start dial movement.

• Take reading for 1 Minute.

• Press lever to stop.

• For precise measurements, use a wand or

extension rod to minimize effects of hand, arm,

and body.



6

Traverse the whole entry when taking an

anemometer reading.

Start

15

Sec.

30 Sec.

45

Sec.

End

60 Sec.



7

Take care to record correct dial reading.

Dial Reading = 239 feet per minute.



8

Correct reading per

correction chart.

Correction factor = +43

Note

Calibration

Due Date

Dial Reading = 239

Velocity = 282



9

Take multiple height measurements for

irregular roof.

5’ 0” 5’ 0” 6’ 6”

Average Height = 5’ 6”



10

Estimate Gob Areas.

4 Feet

Gob area = 1/2 * 3 *4 = 6 feet2

Triangular shaped gob



11

Estimate area of obstruction!

Crib area = 3 * 2.5 * 6 * 50% = 22.5 feet2

Taking air reading between 3 rows of cribs. You have to

estimate the effect of the cribs.



12

Narrow, high

velocity

openings may

require you

to take out

the area of your body !

Air velocity has an impact on the amount of

obstructions you should consider!

Remove 3 feet2 for body and 3 feet2 for timber!



13

Calculations Example

5’ 0” 5’ 0” 6’ 6”

Average Height = 5’ 6” Q = V A

20’

Area = 5.5 X 20 - 6 = 110 ft.2 - 6 ft.2 = 104 ft.2

Q = V A = 282 X 110 = 31,020 cfm

4 Feet

Gob area = 1/2 * 3 *4 = 6 feet2



14

Regulator

Take Air Readings Upwind of Obstructions!

Try to take air readings a few

feet inby corners.

Recommendedlocations to take

air readings.



15

O.67 ft.2

1.33 ft.2

Area of block = 0.67 X 1.33 = 0.89 ft.2

Area of Reg. = 8 X 0.89 = 7.2 ft.2

If cannot take air reading upwind of regulator then take

centerline reading in regulator and multiply by 0.9.

Anemometer Reading = 100 fpmVelocity =100 X 0.9 = 90 fpm

Q = 90 X 7.2 = 648 cfm



16

How to take smoke readings!

It takes two!

Measure how long it takes smoke totravel over a pre-determined distance!

Best for upstream

(smoker) to look down

path of smoke with light.

Divide distance

traveled by time

required to get the

velocity. Multiply by60 to get fpm.

Example: 6 seconds to travel 10 feet.

10/6 = 1.67, 1.67 X 60 = 100 fpm



17

1

2

3

4

5

6

7

8

9

Divide the entry into quadrants to take smoke

readings.

The number of quadrants is flexible!

OR take centerline reading and multiply by 0.9!



18

Mean Entry Velocity

1) Measure area

behind curtain.

2) Take anemometer

reading behind curtain.

3) Calculate airflow

behind curtain.

4) Measure remaining

area of entry.

4 ft.

5 ft.

16 Ft.

5) Divide airflow reading

behind curtain by entry area.

4 X 5 = 20 Ft.2

Velocity = 272 fpm16 X 5 = 80 Ft.

2

272 X 20 = 5,440 cfm

5,440/80 = 68 fpm



19

Ventilation Tubing Area

R 2 Area =

= 3.14

Pie are square!



20

Vent Tubing Example

R 2 Area =

24 inch Diameter Tubing

Area = 3.14 X 12

Area = 3.14 ft.2

Entry Area = 5 X 20 - 3.14 = 97 ft.2

20 ft.5 ft.

Anemometer reading = 2,350 fpm

Mean Entry Velocity = 7,379/97 = 76 fpm

Q=VA

Q=3.14 X 2,350

Q=7,379 cfm



21



22

Airflow in a mine is induced by pressure

differences between intake and exhaust

openings.



23

The pressure difference is caused by

imposing some form of pressure at one

point or a series of points in the ventilatingsystem.

Exhausting Fan



24

The pressure created must be great enough

to overcome frictional resistance and shock

losses.

• Friction pressure losses are caused by the resistance of

the walls on the airstream. Friction losses thereforedepend upon the conditions and roughness of

individual wall surfaces and velocity of air.

• Shock pressure losses are caused by abrupt changes

on the velocity of air movement. Shock lossestherefore are the result of changes on air direction or

of airway areas, obstructions, and regulation.



26

Airflow follows a square-law relationship

between volumes and pressures, that is,

twice the volume requires four times the

pressure.

100,000

CFM

2 inches

W.G.

200,000

CFM

8 inches

W.G.



27

The pressure drop for each split leaving

from a common point and returning to a

common point will be the same regardless

of the air quantity flowing in each split.

R

AB



28

Mine ventilation pressures, with respect to

atmospheric pressures, may be either

positive (blowing) or negative (exhausting).

• Total Pressure = Static Pressure + Velocity Pressure

• Static Pressure is the pressure exerted in all directions.

Tire pressure is static pressure. Can be negative or

positive.

• Velocity pressure is directional pressure. You feel

velocity pressure when you feel the wind. VP isalways positive.

• Exhausting fans are generally rated on Static Pressure.

• Blowing fans are generally rated on Total Pressure.



29

Air always flows from a point of higher to

lower pressure.

* Blowing fans create a high

pressure point immediately inby

the fan. Air travels from this high

point through the mine to the

surface.

* Exhausting fans create a low

pressure point immediately inby

the fan. Air travels from the

surface through the mine to this

low pressure point.



30

Blowing

Fan

* Neutral flows to outside. Smoke

will not travel to face area.

* Gobs are “pressurized”. Less influx

of contaminants from gobs until fan

stops.* Harder to maintain required LOC

quantities.

* Best for mining near OLD

WORKS.



31

Exhausting

Fan* Neutral flows toward face. Smoke

will travel toward face area.

* Gobs are “under suction”.

Contaminants flow from gobs until

fan stops.* Easier to maintain required LOC

quantities.

* Worse for mining near OLD

WORKS.

F V til ti



32

ExhaustingBlowing

Face Ventilation

Higher velocity

at face.

Best for gas.

Worse for dust.

Lower velocity at

face.

Worse for Gas.

Good for Dust.



34

Section 45.1-161.208. Pre-shift Examinations.

C. During the pre-shift examination, the mine

foreman shall determine the volume of air

entering each of the following areas if a miner isscheduled to work in the areas during the

oncoming shift:

1 In the last open crosscut , which means thecrosscut in the line of pillars containing the

permanent stoppings that separate the intake and

return air courses, of each set of entries or rooms

on each working section and areas wheremechanized mining equipment is being installed

or removed.

S i 4 1 161 209 O if i i



35

Section 45.1-161.209. On-shift Examinations.

C. Persons conducting the on-shift examination

shall determine at the following locations which

are underground:

1 The volume of air in the last open crosscut , which

means the crosscut in the line of pillars containing

the permanent stoppings that separate the intakeand return air courses, of each set of entries or

rooms on each working section and areas where

mechanized mining equipment is being installed

or removed.



37

LOC

Where is

Last Open

Crosscut?

LOC

R



38

Section 45.1-161.210. Volume of Air.

A The quantity of air passing through the last open

crosscut shall be not less than 9,000 cubic feet per

minute; provided, however, that the quantity of air

reaching the last open crosscut in pillar recovery

sections may be less than 9,000 cubic feet per minute,if at least 9,000 cubic feet of air per minute is being

delivered to the intake end of the pillar line.

B The air current at working faces shall under all

conditions have a sufficient volume to readily diluteand carry away smoke from blasting and any

flammable or harmful gasses.



39

LOC LOC

Where is

Last Open

Crosscut?

LOC



40

Where is

Last Open

Crosscut?

LOC



41

Section 45.1-161.208. Pre-shift Examinations.

C. During the pre-shift examination, the mine

foreman shall determine the volume of air entering

each of the following areas if a miner is scheduled to

work in the areas during the oncoming shift:

3 The volume of air at the intake end of any

pillar line

1 where a single split of air is used, in the intake

entry furthest from the return air course,

immediately outby the first open crosscut outbythe line of pillars being mined, or

2 if a split system is used, in the intake entries of

each split immediately inby the split point.



42



shall determine at the following locations whichare underground:

4 The volume of air at the intake end of any pillar line

1 where a single split of air is used, in the intake entryfurthest from the return air course, immediately

outby the first open crosscut outby the line of pillars

being mined, or

2 if a split system is used, in the intake entries of each

split immediately inby the split point.



43

Where is

Intake Endof Pillar

Line?

Intake



44

Where is

immediately

inby Spli t

Point ?

Inby Inby



45

LOC

LOC

Where is

Last

Open

Crosscut

?

Wh i



46

Where is

Last

Open

Crosscut?

LOC

LOC

LOC

LOC



S ti 45 1 161 209 O hift E i ti



48



shall determine at the following locations which

are underground:

2 The volume of air on a longwall or shortwall,

including areas where longwall or shortwall

equipment is being installed or removed, in theintake entry or entries at the intake end of the

longwall or shortwall.

3 The velocity of air at each end of the longwall or

shortwall face at the locations specified in the

approved ventilation plan required pursuant to the

federal mine safety law;



49

Where are

Intake Air

Readings

required?

Velocity

Velocity locations

as required by

approved federal

ventilation plan.

Volume



50

Where areIntake Air

Readings

required?

Volume

Velocity

Velocity locations

as required by

approved federal

ventilation plan.



51

Section 45.1-161.210. Weekly Examinations.

D. At least every seven days , a certified person

shall:Determine the volume of air entering the main

intakes and in each intake split;

Determine the volume of air and test for methane in

the last open crosscut in any pair or set of developing

entries or rooms, in the return of each split of air

immediately before it enters the main returns and

where the air leaves the main returns; and Test for methane in the return nearest each set of seals

immediately after the air passes the seals.



52

Section 1

Where are weekly air

readings required?

Main Intake

LOC

Main

Return

Where are weekly air



53

Section 1Where are weekly air

readings required?

Main Intake

Intake Split

Intake Split

LOC

LOCReturn Split

Return

Split

Main

Return

Wh klLOC



54

Section 1Where are weekly

methane test required?

Main Return

LOC

Main

Intake

Methane

Test

Wh kl AiLOC



55

Section 1Where are weekly Air

Readings required?

Main Return

LOC

Main

Intake

ML @

Top End

Entrance to

GOB

R

ML 1



56

Actions for Excessive Methane



57

45.1-161.222. Actions for excessive methane.

Paragraph A

A Tests for methane concentration under this

section shall be made by certified or

qualified persons trained in the use of anapproved detecting device which is

properly calibrated. Tests shall be made at

least twelve inches from the roof, face,ribs, and floor.



58


Paragraph B

B When one percent or more methane is present in a

working place or an intake air course, including

an air course in which a belt conveyor is located,

or in an area where mining equipment is being

installed or removed, work shall cease and

electrical power shall be de-energized in the

affected working place at the equipment exceptintrinsically safe atmospheric monitoring systems

(AMS).

1 2 %



59

Methane

Example

R

1.2 %

1. Stop Work

in No. 2

2. Kill power

to Miner.



60


Paragraph B Continued

• Changes or adjustments shall be made to the

ventilation system to reduce the concentration to

below one percent. Only work to reduce the

concentration of methane below one percent shall

be permitted . This does not apply to other faces in

the entry or slope in which work can safely

continued.

1.2 %



61

Methane

Example

R

1.2 %

1. Stop Work

in No. 2

2. Kill power

to Miner.

3. AdjustVentilation.

45 1 161 222 A ti f i th



62


Paragraph C

C When one and one-half percent or more methane is present in a working place or an intake air course,

including an air course in which a belt conveyor is

located, or an area where mining equipment is being

installed or removed, only work necessary to reducethe methane concentration to less than one and one-

half percent will be permitted and all other personnel

shall be withdrawn from the affected area.

Electrically powered equipment in the affected areashall be de-energized and other mechanized

equipment shall be shut off except of intrinsically

safe atmospheric monitoring systems (AMS).

1.6 %



63

Methane

Example

1.6 %

R

2. Withdraw all

other personnel.

1. Work to

reduce CH4

concentration.

3. De-energize

power.

1.8 %



64

R

Methane

Example

2. Withdraw all

other personnel.

1. Work to

reduce CH4

concentration.

3. De-energize

power.



65


Paragraph D

D When one percent or more methane is present in a

return or split between the last working place on a

working section and where that split of air meets

another split of air, or the location at which the

split is used to ventilate seals or worked out areas,

changes or adjustments shall be made to the

ventilation system to reduce the concentration of methane in the return air to less than one percent.



66

Section 1

Methane

Example 1.2 %

Changes or adjustments shall be

made to the ventilation system

to reduce the concentration of

methane in the return air to lessthan one percent

1.2 %

45 1 161 222 Actions for excessive methane



67


Paragraph D

• When one and one-half percent or more methane is present ina return air split between the last working place on a working

section and where that split meets another split or air or the

location where the split is used to ventilate seals or worked-out

areas, everyone except those persons required to performnecessary work to correct the problem shall be withdrawn

from the affected area. Other than intrinsically safe

atmospheric monitoring systems (AMS), all equipment in the

affected area shall be de-energized at the source. No other

work shall be permitted in the affected area until the

concentration of methane in the return air is less than one

percent.

Active

Section



68

AffectedArea

Section

1.8 %

2. All equipment in the affected

area shall be de-energized at

the source.

1. Withdraw everyone except

those persons required to

perform necessary work to

correct the problem !

3. No other work shall be

permitted in the affected area

until the concentration of

methane in the return air is less

than one percent

Active

Section



69

Section

1.9 %

2. All equipment in the affected

area shall be de-energized at

the source.

1. Withdraw everyone except

those persons required to

perform necessary work to

correct the problem !

3. No other work shall be

permitted in the affected area

until the concentration of

methane in the return air is less

than one percent



70


Paragraph G

G The concentration of methane in a bleeder split of

air immediately before the air in the split joins

another split of air, or in a return air course other

than described in subsections D and E, shall not

exceed two percent.

2. Changes or adjustments shall

b d t th til ti1. Identify



71

R

Active Section

2.5 %

Methane

Example

be made to the ventilation

system to reduce the

concentration of methane in the

return air to less than one

percent

problem!

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