CHAPTER 7

GENERAL LABORATORY SAFETY

3.0 THE LAB ENVIRONMENT

 

3.1  General

    3.1.1  Laboratory Housekeeping

        3.1.1.1  General

        3.1.1.2  Waste Disposal

        3.1.1.3  Bench top Storage

        3.1.1.4  Storage

3.2  Laboratory Equipment

    3.2.1  Knowing the Equipment

    3.2.2  Checking the Equipment

    3.2.3  Transfer of Equipment to Inventory

3.3  Gas Cylinders

    3.3.1  Use

    3.3.2  Hazards

    3.3.3  Safe Practices

3.4  Glassware

    3.4.1  Introduction

    3.4.2  Safe Practices

3.5  Refrigerators

    3.5.1  Use

    3.5.2  Flammable

    3.5.3  Chemical Storage

3.6  Heating Devices

    3.6.1  Use

    3.6.2  Types

    3.6.3  Hazards

    3.6.4  Safe Practices

3.7  Vacuum Systems

    3.7.1  General Safety Rules

    3.7.2  Glassware

    3.7.3  Dewar Flasks

    3.7.4  Desiccators

3.8  Centrifuges

    3.8.1  Responsibility

    3.8.2  General Precautions

    3.8.3  Selection Criteria

3.9  Emergency Eyewash and Showers

    3.9.1  Eyewash/Safety Shower Policy

    3.9.2  Implementation/Procedures

    3.9.3  Eyewash/Drench Hose Checks

3.10  Cryogenic Safety

    3.10.1  Definition

    3.10.2  Types

    3.10.3  General Precautions

    3.10.4  Storage Containers

    3.10.5  Hazards

    3.10.6  Personal Protective Equipment


3.1       General

Laboratories are to be under slightly negative pressure.  This reduces the possibility of contaminants escaping into the hallway or other work areas.  Laboratory doors are not to be propped open. 

3.1.1       Laboratory Housekeeping

3.1.1.1       General

As you walk through a well-kept laboratory, you should note a clean and orderly workplace.

·         Floors should be free of hazards.  Never leave carelessly discarded objects, dropped objects, or spilled material on the floor.

·         Always keep tables, laboratory hoods, floors, aisles, and desks clear of all material not being used.  If bench paper is used, it must be changed when visibly soiled.

·         There should always be clear passageways to exits.

·         Access to the following equipment must not be blocked:

            -  safety showers and eyewashes

            -  fire extinguishers

            -  electrical controls

            -  fire alarm boxes

            -  smoke detectors

·         Sink traps and floor drain traps should be filled with water at all times to prevent the escape of sewer gases into the laboratories.  A schedule should be developed to check this at least weekly.

·         Any frequently used bench apparatus should be kept well back from any edges and secured whenever possible.

 

3.1.1.2       Waste Disposal

·         Broken glass, needles, and syringes should be discarded in special containers identified specifically for those materials.

·         Avoid hazards to the environment by following accepted hazardous material disposal procedures (refer to chapter 10 for complete information on hazardous materials disposal). 

·         Keep combustible waste, including rags, in approved containers.

·         Each lab must have designated areas for the different wastes it produces. 

·         Clean broken glass must be placed in box or other puncture-resistant container and labeled “Clean Broken Glass”.  Environmental Services is responsible for collecting this waste.

 

3.1.1.3       Bench top Storage

·         Only “daily use” quantities should be present on bench tops or in fume hoods or safety cabinets.  Bulk supplies should be stored in cabinets, on shelves, or in flammables cabinets, as appropriate.

3.1.1.4       Storage

·         Sharp or pointed tools should be properly sheathed or stored.

·         Chemical containers should be clean, properly labeled and dated.

·         Clothing should be hung in its proper place, not draped over equipment and benches.

·         Less commonly used equipment should be kept in storage.

 

3.2       Laboratory Equipment

3.2.1       Knowing the Equipment

Laboratories use various types of equipment.  Laboratory personnel must be familiar with:

·         how the equipment operates

·         its safeguards

·         its maintenance

·         Use equipment only for its designated purpose.  

·         Carefully position and secure any apparatus used for hazardous reactions in order to permit manipulation without moving the apparatus until the entire reaction is complete.

3.2.2       Checking the Equipment

Before beginning any job or experiment, make sure that each piece of equipment required for that job is in working order. 

Determine that all equipment:

·         has adequate controls and safeguards

·         is installed in a safe location with adequate ventilation, if required

·         is being used only for its designated purpose 

When special adaptation is required, this should be done only with the assistance of Biomedical Engineering and Electronics.  Refer to Chapter 6 of this Manual.

3.2.3       Transfer of Equipment to Inventory

All equipment that is to be transferred to another location by personnel other than the original laboratory personnel requires completion of decontamination and equipment relocation paperwork (See Appendix B).

Note:  If equipment does not operate properly, immediately remove it from service, and properly label it as inoperative so that it will not be used by other laboratory personnel.

 

3.3       Gas Cylinders

3.3.1       Use

If it is not possible to have gas piped into the laboratory because of design limitations, gas cylinders are needed.

3.3.2       Hazards

A variety of gases are used in laboratories, including those that are:

·         inert

·         flammable, or support combustion

·         toxic, or corrosive

If released into the laboratory, these gases may create hazards such as:

 ·         depletion of oxygen

·         fire

·         adverse health effects

Serious consequences may result if the valve is knocked off a cylinder when it is dropped or knocked over.  If gas is released, the cylinder could become a potentially lethal and highly destructive projectile.

The cylinder can travel through walls much like a torpedo travels through water.  Personnel in adjacent laboratories could be seriously harmed or killed if they are in the path of the cylinder.

3.3.3       Safe Practices

Follow these rules for the safe use of gas cylinders.

·         Secure gas cylinders in racks or holders, or with clamping devices whether full or empty.

·         Check the label for proper contents before using a cylinder for any purpose.  Color coding by suppliers may vary.

·         Close valves and relieve pressure on the regulator when cylinders are not in use.

·         Put caps in place when cylinders are not connected for use.

·         Keep the minimum number of cylinders on hand.

·         Identify full and empty cylinders and label them as such.

·         Prevent sparks, flames, electrical apparatus, or circuits from coming into contact with cylinders.  Do not use direct flames or heat lamps to raise the pressure of a cylinder.

·         Store flammable or oxidizing gases either:

            20 feet apart OR separated by a half-hour fire wallfive feet high.

·         Use only regulators approved for the specific gas.

·         Use only oxygen-compatible threading compounds such as Teflon tape on valve threads for oxygen cylinders.

·         When opening a cylinder valve:

            - direct cylinder opening away from personnel,

            - open valve slowly.

·         If an inert, flammable, or toxic gas cylinder develops a small leak at the valve, or if a leak occurs in any safety device, carefully remove the cylinder to an open space out-of-doors and away from any possible source of ignitions.  Call ENVIRONMENTAL HEALTH & SAFETY/B&C for assistance at ext. 21781.

·         Do not move a gas cylinder UNLESS:

            - an appropriate cart or handtruck is used;

            - the cylinder cap is in place;

            - the cylinder is chained or otherwise secured to the cart.

·         Do not store a cylinder in a hallway.

·         Do not use oil, grease, or other lubricants on the regulator valve or fittings.

·         Do not use oxygen as a substitute for compressed air.

·         Do not lift cylinders by the cap, except with an approved cylinder cart designed for this purpose.

·         Do not tamper with or attempt to repair or replace safety devices on cylinder valves.

·         Do not change a cylinder’s contents by:

            - refilling with a different gas;

            - changing the cylinder’s color;

            - changing the lettering on a cylinder.

·         Do not use wrenches on valves equipped with a handwheel.  If the valve is faulty, segregate the cylinder for return to the manufacturer.

 

3.4       Glassware

3.4.1       Introduction

Accidents involving glassware are a leading cause of laboratory injuries.  These can be avoided by following a few simple procedures.

3.4.2       Safe Practices

·         Handle and store glassware carefully so as not to damage it.

·         Properly discard or repair damaged items.

·         When inserting glass tubing into rubber stoppers or corks, and when placing rubber tubing on glass hose connections:

            - use hand (e.g. leather gloves) and eye protection

            - lubricate tubing and make sure that the ends of the glass tubing are fire polished

            - hold hands close together to limit movement of glass should fracture occur

·         Substitute plastic or metal connections for glass ones whenever possible to decrease the risk of injury.

·         When dealing with broken glass:

            - wear hand protection (e.g. leather gloves) when picking up pieces

            - use tongs if available

            - use a broom to sweep small pieces into a dustpan

            - discard pieces into a container identified “For Broken Glass Only”

·         Never attempt glass-blowing operations without proper facilities

·         Be certain that you have received proper instructions before you use glass equipment designed for specialized tasks that involve unusual risks or potential injury

 

3.5       Refrigerators

3.5.1       Use

Laboratory refrigerators are used for storage of:

·         chemicals

·         biological material

·         drugs

·         other laboratory items that must be kept cold 

Workers who bring food and beverages are often tempted to store them in the laboratory refrigerator.  THIS IS NOT AN ACCEPTABLE PRACTICE.  Store food only in refrigerators that are identified as acceptable for storage of food or beverages.

3.5.2       Flammables

Flammable materials must be stored in refrigerators specially designed for that purpose by the manufacturer.  Refrigerators must be labeled either:

·         “Not for Storage of Flammable Materials”

·         “Acceptable for Storage of Flammable Materials”

Refrigerators used for storage of flammable materials cannot have an ignition source inside the unit (e.g. exposed light switches). 

Refrigerators used for storage of flammable liquids and those used in laboratories must meet the requirements for being laboratory-safe for Class 1, Division 1 locations as described in Article 501 of the National Electrical Safety Code (NFPA No. 70 and NFPA No. 45).

3.5.3       Chemical Storage

·         Never place open containers of materials in a refrigerator. 

·         Seals for chemical containers should be vapor-tight and unlikely to permit a spill if the container is tipped over.

 

3.6       Heating Devices

3.6.1       Use

Electrical devices that supply heat for reactions or separations are commonly found in laboratories.

3.6.2       Types

Electrically heated devices include:

·         hotplates

·         heating mantels

·         oil baths

·         air baths

·         hot tube furnaces

·         hot air guns

·         ovens

3.6.3       Hazards

If used improperly, these devices can cause:

·         electrical hazards

·         burns to the user

3.6.4       Safe Practices

Before using any heating device:

·         Check to see if the unit has an automatic shutoff in case of overheating.

·         Note the condition of electrical cords and have them replaced as required.

·         Make sure it has been maintained as required by the manufacturer.

If using a heated bath:

·         If baths are required to be hot at the start of each day, they should be equipped with a timer to turn them on and off at suitable hours..

·         Never use flammable or combustible solvents in a heated bath unless housed in a chemical fume hood.

·         All glass containers heated in baths can develop cracks not visible to the user.   Handle heated glass with care.

 

3.7       Vacuum Systems

3.7.1       General Safety Rules

The following general precautions should be observed when using vacuum systems. 

·         Every laboratory vacuum pump must have a belt guard in place when it is in operation.

·         The service cord and switch, if any, must be free of observable defects.

·         Use a trap on the suction line to prevent liquids from being drawn into the pump.

·         If vapors are being drawn through the pump, a cold tap should be inserted in the suction line to prevent dilution of the pump oil.

·          Place a pan under the pump to catch any oil drips.

            The following procedures will help to prevent fire or explosion.

IF THE PUMP IS USED . . .

YOU MUST . . .

for vacuum distillation or filtration of organic liquids:

Direct the discharge to an operating hood or other exhaust system.  Discharging into an enclosed space such as a cabinet can cause an explosion.

in an area where flammable gas, vapor, or dust are present:

Ensure that motor, cord, plug, and all electrical parts are rated per the requirements of the National Electric Code (NFPA 70).

3.7.2       Glassware

·         Glassware used for vacuum distillations or other uses at reduced pressure must be properly chosen for its ability to withstand the external pressure of the atmosphere.

·         Only round bottom vessels may be subjected to vacuum unless specially designed such as Erlenmeyer filtration flasks.

·          Each vessel must be carefully inspected for defects such as scratches or cracks.

All vacuum operations must be carried out behind a table shield or lowered hood sash because all vacuum equipment is subject to failure by implosion.  Implosion occurs when atmospheric pressure propels pieces inward creating small fragments which are then propelled outward with considerable force.

3.7.3       Dewar Flasks

Dewar vessels have a vacuum between the walls and some types can be dangerous if they fail.

·         Glass vessels can propel glass into eyes and should be wrapped from top to bottom with cloth tape such as electrician’s friction tape (Mylar tape can be used if transparency is needed).

·         Large Dewars encased in metal and stainless steel vacuum containers do not require wrapping.

3.7.4       Desiccators

Glass desiccators are often subjected to partial vacuum due to cooling of the contents.  They have inherent strains due to glass thickness and the relatively flat surface of the top and bottom. It is strongly recommended that one should either:

·         obtain the available desiccator guard made of perforated metal, or

·         use a molded plastic desiccator which is spherical and has high tensile strength.

 

3.8       Centrifuges

3.8.1       Responsibility

When operating a centrifuge, you are responsible for the condition of the machine, both during and at the end of your procedure. This means:

·         proper loading

·         controlling speed to safe levels

·         safe stopping

·         removal of materials

·         cleanup

3.8.2       General Precautions

Do not attempt to operate an unfamiliar centrifuge until you have received instruction in its proper operation including hazards and emergency procedures.  Ask an experienced colleague to demonstrate procedures.  Read the operation manual, if available.

Problem

Effect

Precaution Against

Unbalanced Load

Damage to seals or other parts

Keep lid closed during operation and shut down; stop rotor if you observe abnormal noises or vibrations.

Broken Tubes

Centrifuge contamination, broken glass

When loading the rotor:

- examine tubes for signs of stress,

- discard tubes that look suspicious.

3.8.3       Selection Criteria

In selecting a centrifuge, carefully consider location, type and use.  Other considerations include: 

·         balance capability for each time the centrifuge is used

·         adequate shielding against accidental “flyaways”

·         suction cups or heel brakes to prevent “walking”

·         lid equipped with disconnect switch which shuts off rotor if the lid is opened

·         Safeguard for handling flammables and pathogens (this may include exhaust ventilation or safe location)

·         positive locking of head

·         electrical grounding

·         locations where vibrations will not cause bottles or equipment to fall off shelves

 

3.9       Emergency Eyewash and Showers

3.9.1       Eyewash/Safety Shower Policy:

All areas that use materials that may be injurious to the eye, where ocular exposure provides a significant potential path of disease transmission, or where otherwise required by code, regulation or industry standard shall be required to develop a vision conservation program, which will include

· a written assessment and policy/procedure outlining activities requiring the mandatory use of eye protection
· the installation and maintenance of eye flushing equipment consistent with UTMB EHS-B&C standard
· training of staff in the requirements of that area’s vision conservation program

3.9.2       Implementation/Procedures:

1.  Job Hazard Analysis/Assessment
Where corrosive and/or materials that can cause irreversible eye or bodily injury are used or infectious materials, a job hazard analysis (JHA) shall be performed and documented by staff knowledgeable in this area.  Note: A simplified checklist for evaluating the need for eyewash/shower installations and an in-depth JHA is provided by EHS-B&C.  The JHA should include such information as the types and quantities of materials in use, frequency and duration of use, and the physical-working environment.  If a hazard exists, the following hierarchy of control shall be followed:

1) Substitute less hazardous materials.

2) Modify equipment and work practices to minimize hazards.

3) If an exposure risk still exists, appropriate personal protective equipment shall also be provided and worn in the work area as well as providing “suitable facilities for quick drenching or flushing of the eyes and body”.

4) Activities requiring the use of eye protection shall be documented in separate Standard Operating Procedures and staff performing these shall be trained to utilize proper PPE.

5) Equipment maintenance and personnel training shall be included where appropriate.  Each plumbed device must be checked weekly by departmental personnel to test equipment performance and to flush debris or bacterial sediment.

2.   Selection/Siting
The recommended practice for installing eyewashes/showers is defined by the American National Standards Institute (ANSI) Z 358.1-12009 Standard, Emergency Eyewash and Shower Equipment.  The ANSI standard shall be followed for new construction and major remodeling projects.  Work areas with plumbing must have plumbed drenching/flushing facilities.

Minimum Requirements: Where flushing facilities are to be installed, they shall meet the following criteria:

1) All new installations shall comply with current ANSI Z358.1-2009 standards.  EHS and FOAM have determined that tepid water valves are not required and cold water supply provides adequate temperature range. 

Existing devices will be evaluated on a case-by-case basis and interim devices will be made available as needed by EHS R/A (i.e., first aid bottles, mobile eyewash units)

2)  These facilities shall be immediately accessible within the area the hazard is present; this is defined as within 10 seconds with no obstructions to interfere with accessibility.

3)  These facilities shall provide 15 minutes of continuous flush at a rate of 0.4 gallons per minute for eye flushing (eyewash unit), 20 gallons per minute for body drenching (full body shower) and 3 gallons per minute for irrigation and flushing of body areas (hand-held drench hose) [1].  Note: The different flow rates are due to the different hazards that may be present and therefore warrant different drenching/flushing requirements.

Ø In addition, these facilities should have the ability to flush both eyes simultaneously and be highly visible.  There also should be no sharp projections in the operating area of the unit and the nozzles must be protected from airborne contaminants.  Finally, these devices must be protected against freezing.
Ø Electrical devices should not be located so as to provide a shock hazard when equipment is activated

The decision to install a full body shower versus a hand-held drench hose or a simple eyewash unit is contingent on the information obtained through the JHA.  Many hazards can be managed and economically addressed by the installation of a flexible hose, eye/face or body shower. 

VOLUNTARY INSTALLATION OF EQUIPMENT
In the case that departments wish to install emergency eyewash/shower equipment when not specifically required, such installations are permissible under the following guidelines:
     • The department must contact EHS-B&C Safety (x21781) to ensure suitability of the equipment and the planned location.
     • The department must adhere to all requirements under Inspection and Maintenance.

3.  Program Development
Departments are responsible for:

4.  INSPECTION AND MAINTENANCE
All eyewashes, emergency showers, and combination devices shall be inspected and maintained in accordance with manufacturer's instructions. All equipment shall be on a routine maintenance schedule as follows:


[1] ANSI Z358.1-1998 (sections 4, 5 and 8)

3.9.3       Eyewash/Drench Hose Checks:

Weekly Check:

1. Ensure that the path to the eyewash/drench hose is not obstructed and that there is no equipment or electrical equipment in zone of water.
2. Verify that nozzle caps are in place to prevent contamination and that the nozzles, nozzle caps, and bowl/sink are clean and sanitary.
3. Place a catch pan or bucket under the unit if a plumbed drain is not available.
4. Actuate valve to full open position. Water must flow within 1 second.
5. Verify that nozzle caps come off when the eyewash or drench hose is activated.
6. Verify that water continues to flow until manually turned off and can be used without requiring the use of the operator’s hands.
7. Look at the flow pattern. It should provide a gentle non-injurious flow. If a dual-stream eyewash, both streams should rise to equal height in a pattern that will flush both eyes simultaneously.
8. Continue to flush until water is clear.
9. Report problems to your building maintenance provider.
10.  Verify signage is in place and legible

Annual Inspection/Flow Test as coordinated by EHS

1.   If there appears to be inadequate flow from the device, perform a flow test. This may be done with a flow meter or by timing the flow into a suitable container. Ensure that fluid flow is not less than 1.5 liters per minute (0.4 gallons per minute) for eyewashes or 11.4 liters per minute (3.0 gallons per minute for eyewash-drench hose combination units.
2.   Inspect all components for corrosion or other damage.
3.   If unit is functioning correctly, document the annual check.
4.   Report problems to your building maintenance provider.

Safety Shower Checks: Annually  (coordinated by EHS & Maintenance):

1.       Ensure that the path to the shower is not obstructed.
2.       Check that valve actuator is within 173.3 cm (69 inches) of the floor.
3.       Place a drum or other container under the unit (unless a serviceable drain that can handle 20 gpm is available and water will not harm building materials).
4.       Actuate valve to full open position. Water must flow within 1 second.
5.       Verify that water continues to flow until manually turned off.
6.       Look at the flow pattern. It should provide a gentle non-injurious flow, and the flow should be substantially dispersed.
7.       Continue to flush until water is clear.
8.        Check that spray pattern has a minimum diameter of 50.8 cm (20 in.) at 152.4 cm (60 in.)
above the surface on which the user stands, and that the center of the spray pattern is located at least 40.6 cm (16 in.) from any obstruction.
9.       If there appears to be inadequate flow from the device, perform a flow test. This may be done with a flow meter or by timing the flow into a suitable container. Ensure that fluid flow is not less than 75.7 liters per minute (20.0 gallons per minute) for showers.
10.   Inspect all components for corrosion or other damage.
11.   If unit is functioning correctly, document the annual check following standard practice of using bar code system.
12.   Plan any needed maintenance.

3.10       Cryogenic Safety

3.10.1       Definition

Cryogenics is low-temperature technology, or the science of ultra-low temperatures.  Any temperature below –73.3°C is usually classified as cryogenic.  Cryogenic temperatures are achieved by the liquefaction of gases. 

3.10.2       Types

The most commonly used is nitrogen.  Others include:

·         helium

·         hydrogen

·         argon

·         fluorine

·         oxygen

·         methane

3.10.3       General Precautions

·         Personnel should be thoroughly instructed and trained in the nature of the hazards associated with cryogenics and how to avoid these hazards. 

·         An employee using cryogenics should have a thorough knowledge of:

            - Procedures

            - Operation of equipment

            - Safety devices

            - Properties of materials used

            - Use of personal protective equipment

·         Equipment and systems should be kept scrupulously clean.

·         Mixing of gases or fluids should be strictly controlled to prevent the formation of flammable or explosive mixtures.  Extreme care should be taken to avoid contamination of a fuel with an oxidant or the contaminant of an oxidant with a fuel.

·         Proper consideration should be given to the properties of the gas involved when venting storage containers and lines.  Venting should always be done outdoors to prevent an accumulation of flammable, toxic, or inert gas in the work area.

·         Dispensing of cryogenic fluids requires the use of hand and full face protection.

3.10.4       Storage Containers

·         Cryogenic fluids are usually stored in well-insulated containers designed to minimize the loss of product due to boil-off.

·         A Dewar flask is the most common container for small quantities of cryogenic fluids.  It is a double walled, evacuated container made of metal or glass.

·         Larger quantities of cryogenic fluid require metal containers, also double-walled, of evacuated construction.

·         Exposed glass should be taped to minimize the flying glass hazard if the container should break or implode.

·         Liquids should be transferred from the metal Dewar vessels with special transfer tubes or pumps designed for that particular application.

3.10.5       Hazards

In addition to the cold hazard associated with cryogenics, other hazards include:

 ·         flammability

·         asphyxiation

·         high pressure gas

·         cryogenic impact on storage containers

Source

Hazard

Hydrogen, methane, acetylene

The gases themselves are flammable.

Oxygen

Its presence will increase the flammability of ordinary combustibles.

Liquefied inert gases

Can evaporate and displace oxygen causing an asphyxiation hazard.

Extremely cold surfaces

Can condense O2 from the atmosphere.

Since liquefied gases are usually stored at or near their boiling point, there is always some gas present in the container.

The large expansion ratio from liquid to gas causes a build-up of high pressure due to evaporation of the liquid.

Materials for cryogenic service must be carefully selected because of drastic changes in the properties of materials when they are exposed to extremely low temperatures.

Suitable Material

Comment

Metals:

stainless steel (330 and other austenitic series), copper,

brass, bronze, monel,

aluminum

Proper soldering is important.

Non-metals:

Dacron

Teflon

Kel-F

Chemical reactivity between the fluid or gas and the storage containers and equipment must be carefully evaluated.

 

3.10.6       Personal Protective Equipment

Plastic vials and other cryogenic storage containers have burst when removed from storage Dewars.

Basic personal protective equipment should be maintained in the laboratory for use when dispensing, removing or placing materials into Dewars (i.e. Full face shield, Cryo gloves, Lab Coat, Heavy duty apron).