1 Outline Airflow Measurements How to take air

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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 2

Three categories of Airflow Measurements • Low Velocity (0 to 120 fpm) • Medium Velocity (120 to 2000 fpm) • High Velocity (>2000 fpm) 3

The principal mechanism for taking medium air velocity measurement is the Anemometer. A high speed anemometer is most often used for high velocity air measurements! 4

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. 5

Traverse the whole entry when taking an anemometer reading. 60 Sec. Start End 45 Sec. 15 Sec. 30 Sec. 6

Take care to record correct dial reading. Dial Reading = 239 feet per minute. 7

Correct reading per correction chart. Dial Reading = 239 Correction factor = +43 Velocity = 282 Note Calibration Due Date 8

Take multiple height measurements for irregular roof. 5’ 0” 6’ 6” Average Height = 5’ 6” 9

Estimate Gob Areas. 3 Feet Triangular shaped gob 4 Feet Gob area = 1/2 * 3 *4 = 6 feet 2 10

Estimate area of obstruction! Taking air reading between 3 rows of cribs. You have to estimate the effect of the cribs. Crib area = 3 * 2. 5 * 6 * 50% = 22. 5 feet 2 11

Air velocity has an impact on the amount of obstructions you should consider! Narrow, high velocity openings may require you to take out the area of your body! Remove 3 feet 2 for body and 3 feet 2 for timber! 12

Calculations Example Gob area = 1/2 * 3 *4 = 6 feet 2 Q=VA Average Height = 5’ 6” 20’ 5’ 0” 6’ 6” 3 Feet 5’ 0” 4 Feet Area = 5. 5 X 20 - 6 = 110 ft. 2 - 6 ft. 2 = 104 ft. 2 Q = V A = 282 X 110 = 31, 020 cfm 13

Take Air Readings Upwind of Obstructions! Recommended locations to take air readings. Try to take air readings a few feet inby corners. Regulator 14

If cannot take air reading upwind of regulator then take centerline reading in regulator and multiply by 0. 9. O. 67 ft. 2 1. 33 ft. 2 Anemometer Reading = 100 fpm Velocity =100 X 0. 9 = 90 fpm Area of block = 0. 67 X 1. 33 = 0. 89 ft. 2 Area of Reg. = 8 X 0. 89 = 7. 2 ft. 2 Q = 90 X 7. 2 = 648 cfm 15

How to take smoke readings! It takes two! Divide distance traveled by time required to get the velocity. Multiply by 60 to get fpm. Best for upstream (smoker) to look down path of smoke with light. Measure how long it takes smoke to travel over a pre-determined distance! Example: 6 seconds to travel 10 feet. 10/6 = 1. 67, 1. 67 X 60 = 100 fpm 16

Divide the entry into quadrants to take smoke readings. 1 4 7 2 5 8 3 6 9 The number of quadrants is flexible! OR take centerline reading and multiply by 0. 9! 17

Mean Entry Velocity 4 X 5 = 20 Ft. 2 272 X 20 = 5, 440 cfm 3) Calculate airflow behind curtain. 1) Measure area behind curtain. 4 ft. 5, 440/80 = 68 fpm 16 Ft. 5 ft. 5) Divide airflow reading behind curtain by entry area. 2) Take anemometer reading behind curtain. Velocity = 272 fpm 4) Measure remaining area of entry. 16 X 5 = 80 Ft. 2 18

Ventilation Tubing Area = 2 R = 3. 14 Pie are square! 19

Vent Tubing Example Area = 3. 14 X 12 Area = 3. 14 ft. 2 Q=VA Area = 2 R Q=3. 14 X 2, 350 Q=7, 379 cfm 24 inch Diameter Tubing 5 ft. 20 ft. Anemometer reading = 2, 350 fpm Entry Area = 5 X 20 - 3. 14 = 97 ft. 2 Mean Entry Velocity = 7, 379/97 = 76 fpm 20

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Airflow in a mine is induced by pressure differences between intake and exhaust openings. 22

The pressure difference is caused by imposing some form of pressure at one point or a series of points in the ventilating system. Exhausting Fan 23

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 therefore depend 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 losses therefore are the result of changes on air direction or of airway areas, obstructions, and regulation. 24

Passageways, both intake and returns must be provided to conduct airflow R 25

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. 26

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. A B R 27

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 is always positive. Exhausting fans are generally rated on Static Pressure. Blowing fans are generally rated on Total Pressure. • • • 28

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. 29

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. 30

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. 31

Face Ventilation Blowing =Higher velocity at face. =Best for gas. =Worse for dust. Exhausting =Lower velocity at face. =Worse =Good for Gas. for Dust. 32

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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: 1 In the last open crosscut, which means the crosscut 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 where mechanized mining equipment is being installed or removed. 34

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 intake and 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. 35

LOC R Where is Last Open Crosscut? 36

LOC R Where is Last Open Crosscut? 37

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 dilute and carry away smoke from blasting and any flammable or harmful gasses. 38

Where is Last Open Crosscut? LOC 39

Where is Last Open Crosscut? LOC 40

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 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. 41

Section 45. 1 -161. 209. On-shift Examinations. C. Persons conducting the on-shift examination shall determine at the following locations which are 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 entry furthest 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. 42

Intake Where is Intake End of Pillar Line? 43

Inby Where is immediately inby Split Point? 44

Where is Last Open Crosscut ? LOC 45

Where is Last Open Crosscut ? LOC LOC 46

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: 2 On each longwall or shortwall in the intake entry or entries at the intake end of the longwall or shortwall face immediately outby the face and the velocity of air at each end of the face at the locations specified in the approved ventilation plan required by the federal mine safety law. . . 47

Section 45. 1 -161. 209. On-shift Examinations. C. Persons conducting the on-shift examination 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 the intake 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; 48

Volume Where are Intake Air Readings required? Velocity locations as required by approved federal ventilation plan. 49

Where are Intake Air Readings required? Volume Velocity locations as required by approved federal ventilation plan. 50

Section 45. 1 -161. 210. Weekly Examinations. D. At least every seven days , a certified person shall: 1 Determine the volume of air entering the main intakes and in each intake split; 2 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 3 Test for methane in the return nearest each set of seals immediately after the air passes the seals. 51

LOC Section 1 Where are weekly air readings required? Main Return Main Intake 52

LOC Section 1 Where are weekly air readings required? Intake Split Return Split Section 2 Return Split LOC Intake Split Main Return Main Intake 53

Section 1 LOC Where are weekly methane test required? Methane Test Main Intake Main Return 54

LOC Section 1 Where are weekly Air Readings required? Entrance to GOB R ML 1 ML @ Top End Main Intake Main Return 55

Actions for Excessive Methane 56

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 an approved detecting device which is properly calibrated. Tests shall be made at least twelve inches from the roof, face, ribs, and floor. 57

45. 1 -161. 222. Actions for excessive methane. 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 except intrinsically safe atmospheric monitoring systems (AMS). 58

1. 2 % 1. Stop Work in No. 2 Methane Example R 2. Kill power to Miner. 59

45. 1 -161. 222. Actions for excessive methane. 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. 60

1. 2 % 1. Stop Work in No. 2 2. Kill power to Miner. Methane Example R 3. Adjust Ventilation. 61

45. 1 -161. 222. Actions for excessive methane. 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 reduce the methane concentration to less than one and onehalf percent will be permitted and all other personnel shall be withdrawn from the affected area. Electrically powered equipment in the affected area shall be de-energized and other mechanized equipment shall be shut off except of intrinsically safe atmospheric monitoring systems (AMS). 62

1. 6 % 1. Work to reduce CH 4 concentration. 2. Withdraw all other personnel. Methane Example R 3. De-energize power. 63

1. 8 % 1. Work to reduce CH 4 concentration. 2. Withdraw all other personnel. R 3. De-energize power. Methane Example 64

45. 1 -161. 222. Actions for excessive methane. 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. 65

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 less than one percent 1. 2 % 66

45. 1 -161. 222. Actions for excessive methane. Paragraph D • When one and one-half percent or more methane is present in a 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 perform necessary 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. 67

Active Section 1. Withdraw everyone except those persons required to perform necessary work to correct the problem ! Affected Area 2. All equipment in the affected area shall be de-energized at the source. 1. 8 % 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 68

Active Section 1. Withdraw everyone except those persons required to perform necessary work to correct the problem ! 2. All equipment in the affected area shall be de-energized at the source. 1. 9 % 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 69

45. 1 -161. 222. Actions for excessive methane. 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. 70

Methane Example 1. Identify problem! 2. 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 2. 5 % R Active Section 71

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