HMC Laboratory Ventilation Management Program

The Harvey Mudd College Laboratory Hood Ventilation Management Program was prepared by Theresa Lauer, Senior Director for Facilities, Emergency Preparedness and Safety. With the cooperation and assistance of Hal Van Ryswyk, John Stauffer Professor and Chair of Chemistry and, Joel Peterson, Assistant Vice President for Capital Projects and Facilities


Harvey Mudd College is committed to providing a safe working and educational environment in our laboratories. This Laboratory Hood Ventilation Management Program (the “Program”) was developed to provide an efficient and effective program for the design, installation, operation, and maintenance of campus laboratory fume hoods and their associated systems to maintain the health and safety of our faculty, staff, students and visitors.

Scope and Application

This Program applies to the ventilation in HMC laboratories and is written for all laboratory ventilation on the HMC campus.  General laboratory safety practices are not included except where they may relate to the ventilation system’s proper function or effectiveness.

HMC laboratories are used for teaching, research, quality control, and related activities. In addition to being suited for the intended use they should:

  • be safe places to work
  • comply with environmental, health, and safety regulations, and
  • meet any necessary criteria for the occupants and technology involved in terms of control of temperature, humidity, and air quality
  • be energy efficient without sacrificing safety, compliance, or space condition requirements

This program does not apply to comfort considerations unless they have an impact on contaminant control ventilation.


The primary purpose of this program is to establish minimum requirements and best practices for HMC laboratory ventilation systems to protect users from physical harm and overexposure to harmful or potentially harmful airborne contaminants generated within the learning and research space. The Program’s requirements also seek to protect property where relevant and account for energy considerations, especially where there is a potential to impact worker health and safety.

The Program describes required and recommended practices for the design and operation of HMC hood ventilation systems used for control of exposure to airborne contaminants.  When combined with appropriate work practices and incorporated as appropriate into standard operating procedures, it shall be effective in achieving a safe working and educational environment for the faculty, staff and students of Harvey Mudd College.

The Program is intended for use by HMC faculty, staff and students; designers when preparing for new and renewed installations; maintenance personnel, and testing and balancing personnel.

Harvey Mudd College Management: Department Chair
  • Provide oversight and allocate sufficient resources
  • Implement and enforce the program; check and act on concepts prescribed in the program and other environmental, health and safety management systems at Harvey Mudd College.
  • Provide leadership.
  • Remove barriers between departments.
Laboratory User
  • Identify and report performance problems.
  • Provide information on potentially hazardous materials.
  • Provide information on procedures, work habits, duration of use, and changes associated with hazardous operations and materials, etc.
  • Utilize laboratory hoods in accordance with operating requirements and safety guidelines.
  • Work with the Chemical Hygiene Officer, Department Chair, or Faculty advisor to ensure appropriate safety systems are being utilized.
Harvey Mudd College Chemical Hygiene Officer
  • Assist laboratory users with recognition and evaluation of hazards.
  • Conduct routine safety audits.
  • Determine suitable control strategies.
  • Establish control objectives and safety requirements.
  • Maintain records of performance.
  • Provide training for users of laboratories.
Harvey Mudd College, Senior Director of Plant Operations and Senior Director of Capital Projects
  • Analyze design options to address hazard assessment findings.
  • Ensure system capability to provide safe, dependable and efficient operation.
  • Ensure proper design, installation, and commissioning of systems.
  • Maintain up-to-date system documentation.
  • Ensure proper personnel training to design, install, commission, maintain and use exposure control devices and ventilation systems.
  • Ensure equipment is not purchased without Department Chair and Chemical Hygiene Officer input.
  • Ensure safety and engineering issues are considered in any space allocation decisions.
  • Maintain all necessary record keeping for each laboratory ventilation system.
Harvey Mudd College, Facilities and Maintenance HVAC Staff
  • Conduct preventive maintenance and repair.
  • Ensure proper functioning of systems.
  • Ensure system dependability.
  • Comply with the Program’s safety procedures and all Lock-Out/Tag-Out procedures.
  • Identify, report, and address all hazards in compliance with the program.
Harvey Mudd College Roles and Responsibilities for Ensuring an Effective Hood Ventilation Program

Hazard Assessment

Appropriate responsible persons, including, but not limited to:  VP for Administration and Finance/Treasurer; the Senior Director for Facilities, Emergency Response and Safety; and Department Chairs shall ensure the existence of an ongoing system for assessing the potential for hazardous chemical exposure.

All responsible persons shall promote awareness that laboratory hoods are not appropriate control devices for all potential chemical releases in laboratory work. The practical limits of knowing how each exposure control device is being or may be used shall be considered when specifying design features, performance criteria (commissioning and routine monitoring), or when seeking energy savings. The responsible person as defined in Table 1 shall be consulted in making this judgment. With an overall goal of providing a safe work space for the end users, the following items shall be considered, and decisions made regarding each element’s relevance following the hazard assessment process:

  • Acceptable exposure concentrations
  • Adequate work space,
  • Air cleaning (exhaust pollution controls),
  • Air supply diffusers and discharge temperature,
  • Alarm system (local and central monitoring),
  • Commissioning (level of formality to be applied),
  • Containment (tracer gas containment “pass” criteria)
  • Decommissioning,
  • Design sash opening and sash configuration (e.g., for laboratory fume hoods),
  • Differential pressure and airflow between spaces and use of airlocks,
  • Diversity factor in Variable Air Volume (VAV) controlled laboratory chemical hood systems,
  • Exhaust discharge (stack design) and dilution factors,
  • Face velocity for laboratory chemical hoods,
  • Fan selection,
  • Frequency of routine performance tests,
  • Hood location,
  • Manifold or individual systems,
  • Redundancy and emergency power,
  • Re-circulation of potentially contaminated air,
  • Preventive maintenance, and
  • Vendor

The following resources are available when conducting hazards assessments:

  • The Harvey Mudd College Chemical Hygiene Plan (CHP) is required where hazardous chemicals are used in the workplace, pursuant to the California Code of Regulations (CCR) Title 8, Section 5191 and enforced by the California Occupational Safety and Health Administration (Cal-OSHA). The CHP contains provisions for protecting employees from health hazards associated with chemicals.
  • The Claremont Colleges Services maintains the Respiratory Protection Program whose elements are implemented by Harvey Mudd College. Contact the Chemical Hygiene Officer or TCCS Environmental Health and Safety for more information.
  • A larger, more comprehensive Safe Laboratory Practices in Chemistry document lists detailed information for the safe use, storage, and disposal of common chemical reagents.
  • The American Chemical Society publication Identifying and Evaluating Hazards in Research Laboratories is a tool to guide researchers in analyzing the hazards in their laboratories. It includes step-by-step suggestions for performing job hazard assessments and development of standard operating procedures.

On site staffing resources include:


Complete and permanent records shall be maintained for each laboratory ventilation system. Records shall include:

  • As-built drawings,
  • Commissioning report,
  • Equipment replacement or modifications
  • Testing and Balance reports,
  • Inspection and routine test reports,
  • Periodic performance and operation reports,
  • Maintenance logs,
  • Reported problems,
  • System modifications, and
  • Written Laboratory Ventilation Management Program

Permanent records will allow a history of the system to be maintained. Records should be maintained to establish a performance history of the system that can be used to optimize operation. Records should be kept for at least the life of the system or until the system is altered.

Laboratory Fume Hood Types

The following is a brief description of the types of fume hoods in HMC laboratories:

  • Auxiliary Supplied Air Hoods – Auxiliary air hoods have a portion of the total volume of exhausted air provided through a plenum located above and outside of the hood face.
  • Bypass Hoods – Bypass hoods have a route for air entering the hood (the bypass mechanism) which opens as the sash closes.
  • Conventional Hoods – Conventional hoods have the hood exhaust volume remain nearly unchanged as the sash position varies from full open to the closed position.
  • Perchloric Acid Hoods – Perchloric acid hoods are specifically designed to safely handle certain types of Perchloric acid work and shall be used for such work.
  • Variable Air Volume (VAV) Hoods – Variable exhaust flow from a laboratory hood has implications for room ventilation.  Additional commissioning requirements may be necessary for these systems.

Design, Construction and Commissioning

In accordance with General Requirements of Mechanical Ventilation Systems 5143 the construction, installation, inspection, testing, and maintenance of exhaust systems shall conform to all requirements of Article 107 of the California Code of Regulations, Subchapter 7. General Industry Safety Orders, Group 16.  Additional guidance may be obtained from the following:

Laboratory Hood Ventilation Rates

The flow rate of Constant Volume hoods and the minimum flow rate of Variable Air Volume hoods shall be sufficient to prevent hazardous concentrations of contaminants within the laboratory fume hood.

When laboratory hoods are used to prevent harmful exposure to hazardous substances, such hoods shall conform to all applicable provisions of Article 107,  Section 5154.1 of the California Code of Regulations.

Flow-Measuring Device for Laboratory Fume Hoods

All hoods shall be equipped with a flow indicator, flow alarm, or face velocity alarm indicator to alert users to improper exhaust flow. The flow-measuring device shall be capable of indicating that the air flow is in the desired range, and capable of indicating improper flow when the flow is high or low by 20%.  The purpose of the flow-measuring device is to provide the hood user with continuous information about the hood’s airflow. One method is to measure the total volume flow through the hood. Another method is to measure the face velocity.

The means of alarm or warning chosen should be provided in a manner both visible and audible to the hood user. HMC hoods are set to alarm at face velocity less than 100 lfm.  Tissue paper and strings do not qualify as the sole means of warning.

As an alternative, if the hood is completely turned off, the hood shall be emptied and decontaminated, and provisions shall be implemented to prevent the hood from back-drafting.

The VAV hood shall be provided with an emergency switch that allows the hood exhaust volume to return to the maximum.

Biological Safety Cabinets

When biological safety cabinets, are used to prevent harmful exposure from bio-hazard agents or bio-hazardous materials or hazardous substances they shall conform to the provisions of this Section 5154.2 and Section 5143, Article 107 of the California Code of Regulations, Subchapter 7. General Industry Safety Orders, Group 16.


All newly installed, renovated, or moved hoods shall be commissioned to ensure proper operation prior to use by laboratory personnel. The commissioning process shall be overseen by a designated responsible person or commissioning authority. The commissioning authority should be someone who represents the interests of the system owner and should be knowledgeable in the design and operation of laboratory ventilation systems. In addition, the commissioning authority should be experienced with collection and analysis of test data. A commissioning team consisting of personnel directly involved in the design, installation, and use of the new or renovated systems should assist the commissioning authority.

A commissioning team might include:

  • Chemical Hygiene Officer
  • Commissioning Consultant;
  • Health and Safety Personnel;
  • Hood Performance Tester;
  • HVAC Controls Expert;
  • HVAC Design Engineers;
  • Laboratory Managers;
  • Maintenance Engineers, and
  • Principal Researchers or Hood Users; TAB (Testing, Adjusting and Air Balance) Leader.

A written commissioning program shall accompany design documents and be approved by the commissioning authority in advance of construction activities. The commissioning plan shall be available to all potential suppliers and contractors prior to bid along with the other project documents. A commissioning plan shall address operation of the entire ventilation system where the hoods, laboratories, and associated exhaust and air supply ventilation systems are considered subsystems. The plan shall include written procedures to verify or validate proper operation of all system components and include:

Preliminary and final commissioning documents shall be issued to the appropriate party(ies) by the Commissioning Authority.

The documents shall include:

  • Commissioning Test Data;
  • Copy of Test and Balance Report;
  • Design Flow Specifications;
  • Laboratory and System Drawings for Final System Design;
  • List of Ventilation System Deficiencies uncovered and the details of how (and if) they were satisfactorily resolved.

Work Practices and Training

General Requirements

User shall establish work practices that reduce emissions and employee exposures.  User shall not modify the interior or exterior components of the hood without the approval of the Chemical Hygiene Officer, Responsible Person, or other appropriate authority in the organization.

The following list concerns only those work practices that relate directly to hood performance and applies when hazardous materials are to be used in the hood.

  • The user shall not lean into the hood so that his/her head is inside the plane of the hood, as defined by the sash, without adequate respiratory and personal protection.
  • Equipment and materials shall not be placed in the hood so that they block the slots or otherwise interfere with the smooth flow of air into the hood.
  • All work shall be conducted at least 6 (15.24 cm) behind the plane of the sash (hood face).
  • The horizontal sash or panels shall not be removed.
  • The hood shall not be operated without the back baffles in place.
  • Flammable liquids shall not be stored permanently in the hood or the cabinet under the hood unless that cabinet meets the requirements the current editions of NFPA 30 and NFPA 45 for flammable liquid storage.
  • The Chemical Hygiene Plan and laboratory standard operating procedures should discuss proper work practices.
  • When large equipment must be placed in a hood, placing the equipment on a stand to allow air to flow under the stand can reduce the significance of any airflow disturbances.
  • Marking the work surface with a tape or other means, to indicate the 6 (15.24 cm) line, will assist the user in identifying the limits of usable space.
  • Although the storage of acids does not pose the same hazard as flammable solvents, the storage of acids under the hood should be in acid-resistant cabinets.
  • Because of the high hazard associated with the storage of chemicals in front of the user at the hood, storage of flammable materials under the hood is not desirable; the Chemical Hygiene Officer should always be consulted.
  • When the sash is raised above the design level, the hood could lose adequate The sash or panels shall be closed to the maximum position possible while still allowing comfortable working conditions.
  • Hood users shall be trained to close the sash or panels when the hood is not in use.
  • The hood user shall not operate with the sashes opened beyond the design opening.
  • Pedestrian traffic shall be restricted near operating hoods.
  • Rapid movement within the hood shall be discouraged.
  • The hood shall not be operated unless verified it is working.


Each hood shall be posted with a notice giving the date of the last periodic field test. If the hood failed the performance test, it shall be taken out of service until repaired, or posted with an appropriate restricted use notice.

The notice shall state the partially closed sash position necessary for safe/normal operation and any other precaution concerning the type of work and materials permitted or prohibited.

Other information that should be posted may include flow rates, fan numbers, an indication that the system is VAV or less than 100% diversity and an emergency phone number.

Operating Conditions

Hoods shall be in operation whenever hazardous volatile materials are being used or stored inside.

Preventive Maintenance

Inspection and maintenance shall follow a Preventive Maintenance (PM) Program as recommended by the manufacturer with oversight by Assistant Vice President for Capital Projects and Facilities.  Preventive maintenance shall be performed on a regular basis and scheduled a minimum of two weeks in advance with the appropriate Department Chair.


Hood users shall be trained in the proper operation and use of a hood prior to using the hood. User shall be trained to report the following:

  • A hood that is more than 10% below the standard operating conditions, either because of inadequate face velocity, or poor distribution of the face velocity should be immediately reported to the responsible safety person lab manager and the Chemical Hygiene Officer. The hood should not be used unless specific conditions for safe use can be identified and posted such as its maximum sash opening.
  • Hoods should only be turned off when all materials are removed from the interior and only if the hood does not provide general exhaust ventilation to the space.

Planned Work

Permit-to-Work for Preventive and Scheduled Work

Obtaining a formal written authorization to work is an effective way of reinforcing control over contractor and maintenance activities pertaining to our laboratory hoods. This type of system and written authorization to perform is known as a Permit-to-Work. A Permit-to-Work is a formal control system against harm to people as well as damage to property and assets.

The following are the rules for a Permit-to-Work system for any work that:

  • could affect the safety of maintenance personnel, hood users or others
  • could jeopardize the integrity of the experiments/procedures/etc., underway in the affected hood(s)
  • requires the hood ventilation system to be compromised so as to reduce or increase the air flow in any one hood by 20%

The permit must specify clearly the following:

  • Job location
  • Work Description
  • Name of HMC staff with oversight and responsibility for the work
  • Duration of Work
  • Identify Hazards
  • List Precautions
  • Identify Safety Equipment to be used
  • Identify Personal Protective Equipment to be used
  • Operational Procedures
  • Name, Signature and contact information of person(s) performing the work
  • Name, Signature and contact information of supervisor with oversight for the worker(s)
  • Name, Signature and contact information of Department Chair authorizing work to proceed
  • Who is to do the work, the time for which the work is to be done (start to finish), the work to be done and the necessary precautions

During the period covered on the permit, no unauthorized persons shall perform work on any other area of the exhaust or laboratory hood equipment being serviced. The HMC Permit-to-Work form can be obtained by contacting the Facilities and Maintenance Office via email at The HMC Permit-to-Work form can be found as a fillable PDF download using your HMC Google Account for access.

Planned or Potential Work That May Cause Loss of Building Exhaust

When a planned loss or scheduled work that has the potential to cause loss of building exhaust the following must be executed:

  • Work shall be scheduled a minimum of two-weeks in advance.  Using the above Permit-to-Work process, the Chair of the Department shall be consulted, notified and sign-off on the Permit-to-Work at the time work is scheduled.  Should notice not be given in the timeframe specified above, any one of the Chairs will have the ability to postpone the planned work.
  • The Chairs, working in conjunction with the Chemical Hygiene Officer, will execute a walk-through of all laboratory spaces in the building(s) containing fume hoods, chemical storage, and hazardous waste storage to assess ongoing work with the potential to produce hazards during the loss of exhaust.
  • Facilities and Maintenance staff shall email a notice shall be sent to faculty, staff and student distribution lists at least two weeks in advance of the work. The notice shall state the time of the work, appropriate safety measures as well as any other pertinent information that may be useful to the community during the planned work.
  • Notice shall be posted a minimum of 10 calendar days on all fume hoods and storage lockers connected directly to the building exhaust system stating the time of the shut-down prohibiting work during the time of the shut-down and re-posted, if necessary, 30 minutes prior to a shutdown.
  • Written notice showing the time of shut-down will also be posted on all possible pedestrian entry points to the building 2 business days prior to the time of work. Immediately prior to the start of work, Facilities and Maintenance staff will check all rooms in the building(s) to make sure the buildings are clear. After confirming the buildings are clear for work, pedestrian entry points will be secured and cautioned off with yellow caution tape and appropriate “BUILDING CLOSED – NO ENTRY” signs. No sooner than 20 minutes after exhaust service has been restored, Facilities and Maintenance staff will remove the door signs and tape to allow access to the building(s).

Planned or Potential Work That May Cause Loss of Individual Hood Exhaust

The following shall apply during a planned maintenance, service or any other scheduled shutdown of a single hood.

  • Operations served by equipment being shut down for inspection or maintenance shall be safely discontinued and secured during the planned work.
  • Lock-out/tag-out procedures shall be implemented.
  • Laboratory workers shall be provided a minimum of two weeks’ advance notice of impending planned work. Permit-to-Work notices shall be placed on each hood advising users of impending planned work. The notice shall include the following:
    • date and time of inspection, maintenance or shut down,
    • planned duration of inspection, maintenance or shut down
    • who to contact for more information
    • who to contact for the duration of the shutdown
  • All toxic or otherwise dangerous materials on or in the vicinity of the subject equipment shall be removed or cleaned up before
  • The written Preventative Maintenance (PM) Program shall identify potential hazards and problems associated with laboratory operations and designate appropriate procedures to mitigate such hazards and problems. This could include, for example, routine inspection of fan belts to ensure that hood exhaust ventilation fans are operating at the designed speeds, hoods are being cleaned to minimize buildup of hazardous chemicals and look for evidence of anyone tampering with the equipment.
  • The written program shall identify standard operating procedures to be followed during PM
  • All appropriate “responsible persons” should be involved in the development and operation of the PM
  • If possible, equipment to be removed should be If the maintenance activities involve contact with potentially contaminated parts of the system, these parts should be evaluated first by appropriate methods and qualified persons.
  • Maintenance personnel shall be trained and required to use appropriate PPE (such as respirators, goggles or face-shields, gloves, and protective clothing) during parts of the work involving potential hazard.

Unplanned Loss of Exhaust Ventilation

Unplanned Loss of Building Exhaust

When an unplanned loss of building exhaust occurs, the following must be executed:

  • All persons in the building and surrounding adjoining Libra Complex areas, including basements and sub-basements must evacuate the building immediately. To facilitate the evacuation, the person who identified the loss in building exhaust, will activate the fire alarm using the nearest fire alarm pull station. The same person shall notify (or cause to be notified) Campus Safety at 909.607.2000, that the building is being evacuated due to an unscheduled loss of building exhaust. The notifying person shall also request Campus Safety notify the appropriate Facilities and Maintenance person of the issue so they may respond to resolve the loss of exhaust.  Once Campus Safety is notified, there is no need to call 9-1-1 unless someone is trapped or otherwise unable to exit the building or there is an injury requiring emergency medical attention
  • Facilities and Maintenance staff shall email notice to faculty, staff and student email distribution lists as soon as possible so as to advise the community of the unplanned loss, safety precautions/considerations and any additional information that will be helpful to the community regarding the loss.
  • The automatic fire doors connecting to the adjoining buildings within the Libra complex should close and remain closed until the building(s) is cleared for occupancy. All persons shall remain outside the building(s). Facilities and Maintenance staff shall secure and caution off all pedestrian entrances with yellow caution tape and appropriate “BUILDING CLOSED – NO ENTRY” signs.
  • Properly trained Facilities and Maintenance staff using appropriate Personal Protective Equipment may enter the building as needed to re-establish proper operation of the building exhaust.
  • When the exhaust system is operational and has run continuously for a minimum 20 minutes after the evacuation event is ended, the building can be cleared for occupancy by the appropriate Facilities and Maintenance staff member. Facilities and Maintenance staff shall remove signs and caution tape from the pedestrian entrances after the building has been cleared for occupancy.

Unplanned Loss of Single Hood Exhaust

When single hood alarms and planned work is not being conducted, the following must be executed:

  • Laboratory fume hoods are set to alarm when air velocity drops below 100 lfm. If this occurs while work is being performed, adjust sash in order to adjust air flow velocity. If hood continues to alarm, discontinue work, cap all open containers and close hood sash. Immediately notify Facilities and Maintenance of the issue. Evacuate the room if all chemicals in the hood cannot be contained by capping containers, if fumes are noted or there is concern for the safety of the room occupants. Close laboratory door and post a notice identifying the room is closed until further notice due to a fume hood concern. To facilitate the evacuation, the person who identified the need to evacuate shall execute a room evacuation by notifying others in the room. If that does not effectively facilitate an evacuation of the room, the building fire alarm shall be activated using the nearest fire alarm pull station.  The person who identified the need to evacuate shall notify (or cause to be notified) Facilities and Maintenance staff of the alarming hood so they may respond to resolve the issue.  If the fire alarm is activated to effectuate room evacuation, follow notification procedures associated with fire alarm activation.
  • If the issue cannot be resolved in a timely manner and the chemicals in the hood can be safely moved to another fully operational hood by the trained user or another appropriately trained responsible person the hood shall be posted as, “OUT OF SERVICE, DO NOT USE” until it can be properly repaired for use. Facilities and Maintenance shall notify the Department Chair of the immediate findings and keep the Chair updated until the hood is repaired and returned to service.

A print copy of this program can be obtained by contacting Theresa Lauer, Senior Director for Facilities, Emergency Preparedness and Safety, by phone at 909.607.2760 or by email at