7.1 Machinery Safety Strategy

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Safety StrategyIncluding Risk Assessment & Reduction

Customer:Product/Process:Document Owner:Project or Organization Role:Date of manufacture:


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Introduction

In order to achieve a proper safety strategy there must be a:

1 - RISK ASSESSMENT based on a clear understanding of the machine limits andfunctions which must then be analyzed to identify which ones pose a potential

hazard. The degree of risk due to the hazard is then estimated in order to providea basis for judgement at later stages. A risk evaluation is then required todetermine if existing safety measures are satisfactory or whether additional

measuresare required to reduce the risk.

2 - RISK REDUCTION is then performed if necessary and safety measures areselected based on the information derived from the risk assessment stage. Afterthe implementation of these measures the process is repeated to determinewhether safety has in fact been achieved. The manner in which this is done is thebasis of the SAFETY STRATEGY for the machine.

A series of checklists should be followed to ensure that all aspects are consideredand that the overriding principle does not become lost in the detail.

The first step is to ensure that the whole process is documented. Not only willthis ensure a more thorough job but it will also make the results available forchecking by other parties. It can also be included in the technical file whichsupports the Declaration of Conformity for the Machinery Directive. Because theprocess is likely to be repeated, the documenting of the results means thatneedless repetition can be avoided.

Emergency Stop

An Emergency Stop is a function designed to avoid hazards which are emergingor which already exist and which could cause injury to personnel (hazards arisingwhen faults occur)

Safety requirements of emergency stops:

the Emergency Stop function must be available and able to operate at alltimes,

the Emergency Stop must operate on the positive action principle (defined

in standard EN 292),

the Emergency Stop may be category 0 (immediate cutting off of power tothe actuator) or category 1

(controlled stop; power to the actuators is maintained until they can stop themachine; power is cut off when stopping has been achieved).


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Hazard Identification Checklist

PLANT HAZARD IDENTIFICATION EHS Manual

Hazards Present - Mechanical YES NO Comments

Crushing

Shearing

Cutting/severing

Entanglement

Drawing in or trapping

Impact

Stabbing/puncture

Friction/abrasion

High pressure fluid ejection

Hazards Present Electrical YES NO Comments

Contact with live parts

Approach to live parts

Electrostatic phenomena

Thermal radiation

Hazards Present - Thermal YES NO Comments

Excessive heat/burns/scalds

Excessive cold

Hazards Present Radiation YES NO Comments

Low frequency

Radio frequency andmicrowaves

Infra red

Visible light

Ultra violet

X and Gamma rays

Alpha/Beta rays electron or ionbeams

Neutrons

Hazards Present - Materials YES NO Comments

Contact or inhalation of harmfulsubstances

Explosions or fire


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Risk Estimation Calculation

All machinery that contains hazards presents risk. It is important to be able todescribe at which point the risk lies on a relative scale from minimum tomaximum.

The following pages provide a practical method for achieving this. It has beenshown to be both simple to use and reliable as a guideline to a logical approach.

The risk associated with a particular situation or technical process is derived froma combination of the following elements:

Risk factor Related to the considered hazard

Severity Of the possible harm for the considered hazard

Probability Of occurrence of that harm

Frequency Of exposure to that harm

Number ofPersons

At risk from the considered hazard

The risk factoris determined from a points system calculated as follows:

Risk Factor = Severity x Probability x Frequency x Persons

The value obtained from this risk factor calculation can be used to determine thelevel of risk from the following table:

Risk Level

0 to 1 Negligible

1 to 5 Very Low5 to 10 Low

10 to 50 Significant

50 to 100 High

100 to 500 Very High

500 to 1000 Extreme

Above 1000 Unacceptable


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LOW RISKShould be mainly routine and as such to avoid Complacency a guideline such as safe working practices are introduced invoking constant review andreminders such as adding as part of a Tool Box Talk.

SIGNIFICANT RISK Need to be controlled by implementation of control measuresto reduce the risk.

HIGH RISK Should be controlled by implementation of significant controlmeasures to reduce the risk and as a minimum be reviewed by all relevant

parties prior to commencement to ensure everyone is aware of there own andothers responsibilities.


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Probability

0 Impossible - cannot happen

0.1 Almost unlikely - possible in extremecircumstances

0.5 Highly Unlikely - though conceivable1 Unlikely - but could occur

2 Possible - but unusual

5 Even chance - could happen

8 Probable - not surprised

10 Likely - to be expected

15 Certain - no doubt

Severity

0.1 Scratch or bruise

0.5 Laceration or mild ill health

1 Break of a minor bone or minor illness(temporary)

2 Break of a major bone or minor illness(permanent)

4 Loss of Limb, eye / serious illness of temporarynature

8 Loss of Limb, eyes / serious illness of permanentnature

15 Fatality

Frequency of Exposure

0.1 Infrequently

0.2 Annually

1 Monthly

1.5 Weekly

2.5 Daily

4 Hourly

5 Constantly

Number of persons at risk

1 1 - 2 persons

2 3 - 7 persons4 8 - 15 persons

8 16 - 50 persons

12 50 + persons


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RISK ESTIMATION FORM

Project Title Project .

Sheet

Nature of hazard

Assessment

LO FE DPH NP HRN

Degree of Risk

LO Likelihood of Occurrence FE Frequency of Exposure0 Impossible - cannot happen 0.1 Infrequently0.1 Almost unlikely - possible in extreme circumstances 0.2 Annually

0.5 Highly unlikely - though conceivable 1 Monthly

1 Unlikely - but could occur 1.5 Weekly

2 Possible - but unusual 2.5 Daily

5 Even chance - could happen 4 Hourly

8 Probable - not surprised 5 Constantly

10 Likely - to be expected

15 Certain - no doubt

DPH Degree of Possible Harm NP Number of Persons at Risk0,1 Scratch or bruise 1 1 - 2 persons

0.5 Laceration or mild ill health effect 2 3 - 7 persons

1 Break of a minor bone or minor illness (temporary) 4 8 - 15 persons

2 Break of a major bone or minor illness (permanent) 8 16 - 50 persons4 Loss of Limb, eye / serious illness of a temporary nature 12 50 + persons

8 Loss of Limbs, eyes / serious illness of a permanent nature

15 Fatality

RISK Negligible Very Low Low Significant High Very High Extreme Unacceptable

HRN 0 - 1 1 - 5 5 - 10 10 - 50 50 - 100 100 - 500 500 - 1000 Above 1000

Note : When the HRN is significant or above, some formal action is required.

Recommended safety procedures

Re-Assessment

LO FE DPH NP HRN

Degree of Risk

Further risk reduction required (Yes/No): No

Assessment carried out by Signature:

Position : Date :

Review date(s) :

Selection of Safety Related Control System


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This is that part of the control system of the machine which prevents a hazardouscondition from occurring. The risk estimation is used in conjunction with thefollowing table and charts to determine the safety category:

Degree of possible harm

S1 Slight injury (DPH 1)

S2 Serious and permanent injury to or death of a person (DPH 2)

Frequency of exposure

F1 Rare to fairly frequent (FE 1)

F2 Frequent to permanent (FE 1.5)

Possibility of preventing the accident

P1 Possible in certain circumstances

P2 Virtually impossible

CATEGORY B- Safety related parts of machine controlsystems and/or their protective equipment,as well as their components, shall be

designed, constructed, selected, assembledand combined in accordance with relevant

standards so that they can withstand the

When a fault occurs it can lead to a loss of the

safety function.


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expected influence.

CATEGORY 1- The requirements of category B applytogether with the use of well tried safety

components and safety principles.

As described for category B but with highersafety related reliability of the safety related

function. (The higher the reliability, the less thelikelyhood of a fault

CATEGORY 2- The requirements of category B and the

use of well tried safety principles apply.- The safety function(s) shall be checked at

machine startup and periodically by themachine control system. If a fault is

detected a safe state shall be initiated or ifthis is not possible a warning shall be

given.

The loss of safety function is detected by the

check.

The occurrence of a fault can lead to the loss ofsafety function between the checking intervals.

CATEGORY 3- The requirements of category B and theuse of well tried safety principles apply.

- The system shall be designed so that asingle fault in any of its parts does not lead

to the loss of safety function.

When the single fault occurs the safety functionis always performed.

Some but not all faults will be detected.

An accumulation of undetected faults can lead


CATEGORY 4- The requirements of category B and theuse of well tried safety principles apply.

- The system shall be designed so that asingle fault in any of its parts does not lead


-The single fault is detected at or beforethe next demand on the safety function. Ifthis detection is not possible then an

accumulation of faults shall not lead to aloss of safety

function.

When the faults occur the safety function isalways performed.

The faults will be detected in time to prevent

the loss of safety functions.

has determined from the risk estimation that requires . This will be implemented using

/ with thefollowing control devices:

Guard door interlock switch

Emergency stop pushbutton switch

Emergency stop Pull wire

ASi safe network

Fortress/Castell trapped key

Safety Shutters/fire doors

Safety mats

Light curtains

Programmable proximity sensors

Fixed guarding

Limit switches


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Control System General Description

The Main Panel Assembly will house the following major components:

1. Main incoming Fuse / Switch2. 24VDC control circuit supply and distribution

3. Emergency Stop Relays and associated circuitry4. Siemens S7 315-2 Processor c/w Profibus DP Interface

5. Siemens S7 Industrial Ethernet Module6. Siemens OP3 HMI (door mounted)

7. Multiplexer for Barcode Scanners8. Power distribution to Barcode Scanners9. DOL Conveyor Drive (16 off), comprising:

Motor Protection Circuit Breaker

Triple Pole Contactor(s)

Set of Control Terminals

All equipment has been manufactured in accordance with relevant Britishstandards, (including Health and Safety). As far as possible componentshave be selected to be suitable under fault conditions to give Type 1 co-ordination to IEC.947 and internal assembly segregation is in accordance

with BS EN 60439-1 (Form 2A)

Enclosures are supplied in the manufacturers standard finish RAL7035 orequivalent. Enclosures are adequately ventilated, details of thermal

design calculations can be found in

Supply Voltage: 400VAC 50Hz 3 Phase

Control Voltage: 24VDC

Design Current Amps

Ambient temperature limits -5C to +40C

The minimum requirements for the intended installation site are a weatherprotected location having neither temperature nor humidity control. There

should be a negligible probability of the presence of water and installationaltitude should be less than 2000m above sea level.

Isolating switches are On-load type capable of breaking stalled motorcurrent in accordance with BS EN 60947 3.

A dedicated area of the main control panel is provided for the distributionof power supplies to the internal electrical equipment.

All panel wiring has been carried out in PVC insulated copper cable toBS6231 unless otherwise specified on electrical schematics and is ofappropriate current ratings. Wiring is run in PVC trunking where spacepermits. Wiring not run in trunking has been loomed in a neat

workmanlike manner. The electrical panel has been fully inspected and tested during

manufacture. A schedule of testing and test results may be found in

The control cabinet accommodates all the electrical equipment enabling

the functioning of the machine to be monitored and controlled.

The danger area is fully guarded on all four sides. This guard takes theform of fixed guarding with access doors.

All guards are electrically interlocked and remove power to motors, all

solenoid valves and the rotary table in the event a guard is opened.

The hazardous machine functions protected by the guard cannot operateuntil the guard is closed. The closing of the guard will not initiate any

machine functions until the emergency stop circuit is reset by a separateaction.


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The electrical control circuit is continually monitored and if a failure occursthe safety interlock will activate. It will not be possible to run the machineuntil the fault is cleared and circuit reset.

This machine is intended to be operated by skilled persons (includingoperators, maintenance personnel and technicians) within a heavyindustrial environment.

After setting, the machine is designed to run unmanned, although manualintervention is occasionally required to rectify alarm conditions.

The general public will not have access to the machine, althoughcustomers and visitors may walk past the machine during site visits andinspections. In this case visitors will be limited to designated walkways

and not permitted access to the machine.


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Risk Reduction

Section 1.1.2(b) from schedule 3 of the Machinery Directive explains that thereare three basic methods to be considered and used in the following order:-

Eliminate or reduce risks as far as possible by inherently safe machinerydesign.

Take the necessary protection measures in relation to risks that cannot be

eliminated.

Inform users of the residual risks due to the shortcomings of theprotection measures adopted, indicate whether any particular training isrequired and specify the need to provide personal protection equipment.

have implemented the following measures, or safe workingpractices to reduce the levels of risk:

Machine movements

The machine uses a number of guard operated interlocking devices withtongue operated switches. The tongue is fixed to the guard so that it

cannot be easily removed. The guard also uses direct (mechanical)locking. This is not connected to the control circuit.

The canopy and hinged doors must be fitted. All interlocks and emergency

stops must be tested weekly. When in normal use the door locks must befitted and locked.

Switch off machine power and compressed air supply before enteringmachine. Ensure operator is wearing suitable clothing, ie, one-piece fittingoverhauls. No loose clothing.

Electric Shock

Electrical control systems meet the requirements of BS EN 60204:1998.

Electrical control cabinets are interlocked.

Ensure electrical connections from mains are safe. Only authorizedpersons are to work with electrical systems.

Electrical wiring Look for obvious signs of hardened or damaged cable and

replace before testing machinery.

Power supply cable. Look for obvious signs of wear on armored cablesupply. Ensure power can be isolated as required. Ensure fittings are

sound.

Power Tools. Do not use power tools with wet hands. If any doubts about

safety of tool refer to Works Manager. Ensure ring main is earthed.

Hot machine parts

Ensure machine guards in place and/or wear protective clothing

Use suitable protective clothing, including flame retardant gloves and facemask

Noise

The wearing of ear plugs is recommended..

Blow Moulding Testing, Ensure fitting of suitable air silencers to exhaust

valves. Factory Compressors. Sited in separate building. Wearing of ear plugs


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Pressurised Systems

All high pressure flexible hoses are fitted with whip checks. Exerciseextreme caution when working on hydraulic valves and pipes. Ensuremachine is switched off. Wearing of protective gloves recommended ifpossible.

High pressure compressor system in factory, air compressor, booster (ifrequired) and receiver should be located in a separate area. Do notinterfere with any high pressure apparatus. If experiencing air problems

inform your works manager who wilt in turn contact outside compressedair specialists.

Documents

7.1 Machinery Safety Strategy