Hazard Monitors for Grain Elevators

Johnny Wheat

Brian Knapp

4B

Components

Limited

PRESENTED BY:

Copyright 2012 © 4B Components Ltd. All Rights Reserved

Combustible Dust

(Fuel)

Dispersion

of Dust Particles

Ignition Source

(Heat)

Confinement

of the Dust Cloud

Oxygen in Air

(Oxidizer)

YOUR PROBLEM: Grain dust is explosive

YOUR SOLUTION: Remove one of the elements from

the dust explosion pentagon


Common Ignition Sources:

1. Belt Slip

2. Belt Misalignment

3. Hot Bearings


If you eliminate these ignition sources then you not only

considerably reduce your chance of having an

explosion, but you also realize every day values of:

1. Improved Preventative Maintenance

2. Smoother Running Equipment

3. Longer Service Life for Equipment


YOUR PROBLEM: Belts slipping on the head or drive pulley of a

machine is an ignition source

YOUR SOLUTION: Install a speed switch at the tail end of the bucket

elevator or conveyor to warn when the belt starts

to slip and automatically stop the machine

Sensor

M800 Elite Speed Switch


Standard 1910.272(q)(5)

The employer shall equip bucket elevators with a motion detection

device which will shut-down the bucket elevator when the belt speed

is reduced by no more than 20% of the normal operating speed.


YOUR PROBLEM: Belts misaligning and rubbing against a machine’s

casing is an ignition source

YOUR SOLUTION: Install belt misalignment sensors at the drive and

tail ends of the bucket elevator to warn when the

belt starts to rub and automatically stop the machine

Sensor

Sensor

Touchswitch


Standards 1910.272(q)(6)(i) & (q)(6)(ii)

Equip bucket elevators with a belt alignment monitoring device which will

initiate an alarm to employees when the belt is not tracking properly.


YOUR PROBLEM: Bearings overheating are ignition sources

YOUR SOLUTION: Install bearing temperature sensors on all critical

bearings such as the drive and tail bearings to warn

when a bearing reaches a high temperature and

automatically stop the machine Sensor

Sensor

ADB Bearing Temperature Sensor


Standard 1910.272(q)(4)(ii)

Provide vibration monitoring, temperature monitoring, or other means

to monitor the condition of those bearings mounted inside or partially

inside the leg casing.


YOUR PROBLEM: Electrical equipment can itself, be an ignition

source for a grain dust explosion

YOUR SOLUTION: Only install equipment approved / listed and

certified by an NRTL (Nationally Recognized

Testing Laboratory)

Class II Division 1 Group G -

• For example, inside a bucket elevator or belt conveyor

Class II Division 2 Group G -

• For example, outside a bucket elevator or belt conveyor


YOUR PROBLEM: You are not confident that your local electrical

service supplier has the experience and knowledge

required to professionally install a hazard monitoring

system

YOUR SOLUTION: 1. Send your electrician to the manufacturers

facility for training on the equipment to be installed

2. Have the manufacturer install the system or

recommend a suitable installer


YOUR PROBLEM: Operators continue to operate equipment despite

hazard monitoring systems indicating that there is

a hazardous condition

YOUR SOLUTION: 1. Educate operators on the hazards of grain dust

explosions

2. Instruct operators of the severe penalties that

will be enforced if they do not follow company

policy

3. Automatically log all alarms and shutdowns so

that operators understand that there is a

permanent record and they are accountable


YOUR PROBLEM: Equipment does not perform to your expectations

YOUR SOLUTION: 1. Inspect the system and installation

2. Commission the system

3. Test the system, both initially and periodically

4. Train the operators and management on the

capabilities, use, maintenance and testing of the

system


YOUR PROBLEM: A sensor or control is damaged and the only way

to run equipment is by electrically bypassing the

hazard monitoring system

YOUR SOLUTION: DO NOT RUN IN BYPASS. Have spare sensors

and components available for immediate

replacement so that down time is reduced to a

minimum

! ! ! WARNING ! ! !


Standard 1910.272 App A

It is imperative that the prearranged schedule of maintenance be

adhered to regardless of other facility constraints. The employer

should give priority to the maintenance or repair work associated with

safety control equipment…

(See Actual Standard For Full Interpretation)


YOUR PROBLEM: 1. OSHA has stepped up its facility inspection and

audits in conjunction with their National Emphasis

Program (NEP) on dust explosions

2. OSHA is finding twice as many violations in

relation to the NEP inspections compared with all

other types of facilities. One such violation is that

bucket elevators and conveyors are not equipped

with bearing temperature, belt alignment and

underspeed detection monitors

YOUR SOLUTION: 1. Understand the dangers of grain dust, and

implement a program of compliance to not only

OSHA regulations, but also NFPA and other

standards

2. Install hazard monitors (as discussed earlier) to

help eliminate ignition sources


OSHA & NFPA STANDARDS (See Actual Standard For Full Interpretation: OSHA 1910-272, NFPA 61, NFPA 654)

Hazard Requirement

Belt Slip Motion detection device to provide a shutdown and alarm at 20% reduction in normal belt speed. Also shutdown of feeding equipment.

Belt Misalignment Belt alignment monitoring devices at head and tail pulleys, which initiate an alarm.

Bearing Failure Bearing temperature or bearing vibration monitors which activate and alarm.

Pulley Misalignment Head pulley alignment monitors which activate an alarm.

Plugged Spout Sensors which provide a shutdown and alarm when there is a plug condition. Also shutdown of feeding equipment.


o NFPA 61 Standard for agricultural and food

processing industry (rev. 2008)

o NFPA 68 explosion venting standard (rev. 2007)

o NFPA 69 prevention standard (rev. 2008)

o NFPA 70 NEC (rev. 2008)

o NFPA 77 static electricity (rev. 2007)

o NFPA 499 guide to combustible dust area

classifications (rev. 2004)

o NFPA 654 standard for general industry (rev. 2006)

NFPA STANDARDS


TYPICAL SENSORS FOR HAZARD MONITORING

Speed &

Belt Slippage Belt Misalignment

Bearing

Temperature


TYPICAL CONTROLS FOR HAZARD MONITORING

Watchdog™ Elite

Single Machine

Hazard Monitor

PLC T500 Hotbus™

Multi Machine

Hazard Monitor


QUESTIONS?


Business

Hazard Monitors for Grain Elevators