Stanford University Gas Cabinet Installation and Performance Criteria I. Application Gas cabinets are ventilated enclosures that are used to isolate hazardous gas cylinders from the surrounding work place. This protocol is to be used by Stanford University in-house personnel (e.g., HVAC Shop) and qualified contractors to certify ventilation performance of new gas cabinets during the commissioning phase of new buildings or renovations, and to annually re-certify gas cabinets in existing buildings. II. Regulations Gas cabinets are subject to the regulatory requirements of: Santa Clara County Toxic Gas Ordinance, Section B11-384(b) Fire Code, 2007 California Fire Code: 2703.8.6 and 3704.1.2 Cal/OSHA, 8 CCR 5143(a)(5) III. Operational Requirements A) Equipment Requirements: Gas cabinets shall have the following features: 1. be constructed of steel (12 gauge min.) and be appropriately listed by UL or FM, or approved by local fire authority 2. have interiors that are treated, coated, or constructed of materials that are compatible with material being stored used 3. have a corrosion-resistant fire sprinkler installed inside the cabinet, if used with Highly Toxic or Toxic materials 4. be provided with self-closing doors 5. be provided with self-closing access ports or fire-rated windows 6. be provided with automatic fire sprinkler systems, when required 7. be provided with continuous gas detection equipment, when required. B) Installation Requirements: When gas cabinets are installed, gas cabinets shall: 1. be connected to a treatment system (if used with Highly Toxic 1 or Toxic 2 materials) 2. be seismically anchored 3. labeled with chemical name, hazard class of gas, concentration of mixtures, indicate to tool or apparatus it feeds, along with NFPA 704 diamond sticker with hazard ratings. C) Storage Requirements: The maximum number of cylinders that may be stored/used in a gas cabinet is three. Exception: For lecture bottles which are less than 1 lb, 100 cylinders of Highly Toxic or Toxic materials may be stored/used in the gas cabinet. 1 Highly toxic gases as defined by the Fire Code have an LC50 (median lethal concentrations in air) no more than 200 ppm. 2 Toxic gases have an LC50 greater than 200 ppm and no more than 2000 ppm.
D) Performance Criteria: Gas cabinets shall operate: 1. with an average face velocity at face of access ports or windows of 200 fpm with no point less than 150 fpm 2. with inward flow 3. at negative pressure in relation to their surrounding area E) Frequency of Certification: The gas cabinet must be certified following Attachment A Stanford University Gas Cabinet Certification Protocol according the following schedule: 1. upon installation 2. annually 3. after alterations or maintenance F) Notification: Project managers are responsible for informing the appropriate department as indicated below when gas cabinets are coming on line so that the gas cabinet is integrated into the annual certification process: For main campus, contact: Stanford University s HVAC Shop: 723-3360 For School of Medicine, contact: Engineering & Maintenance at 723-5555.
Attachment A Stanford University Gas Cabinet Certification Protocol A. Qualitative Evaluation - Smoke Test (Note: This section demonstrates inward flow and that gas cabinet is under negative pressure in relation to area) Equipment/ Materials Required For Certification Titanium tetrachloride, dry ice in water, or other means of visualizing airflow Leather gloves if dry ice is used, latex gloves if other means are used 1) From open face of access port and location around gas valves, dispense smoke in direction perpendicular to exhaust flow. 2) Observe flow patterns to see if the smoke is contained within the gas cabinet. 3) Record all collected data on SU Gas Cabinet Certification Form, or equivalent. 4) If the smoke is contained, the gas cabinet fulfills this portion of the test. B. Quantitative Evaluation - Face velocity measurement Equipment/ Materials Required For Certification Thermal anemometer (calibrated as specified by manufacturer) Tape measure 1) Take face velocity measurements in the face plane (access port) of the opened window For square windows: a) divide the opening into quarters by bisecting the height and width; b) take velocity measurement in the center of each quarter; c) document measurements. For rectangular windows: a) divide the width into thirds and height into halves; b) measure the center of each sixth; c) document measurements. 2) Calculate average face velocity. 3) Record all collected data on SU Gas Cabinet Certification form, or equivalent. 4) If average face velocity is greater than or equal to 200 fpm; and minimum velocity is no less than 150 fpm, the gas cabinet fulfills this portion of the test. C) Equipment Inspection 1) Self Closing Doors: Open gas cabinet doors and observe that they close automatically and latch. 2) Self Closing Windows/Ports: Open gas cabinet windows/ports and observe that they close automatically close. 3) Record all findings on SU Gas Cabinet Certification Form, or equivalent. D) Passing/Failing Gas Cabinets For units that PASS: 1) If the gas cabinet meets sections A, B and C of this protocol: (a) document that unit has passed using SU Gas Cabinet Certification form, or equivalent, and (b) apply certification SU Gas Cabinet Certification Sticker, or equivalent. SU Gas Cabinet Survey
Gas Cabinet ID #: Average Face Velocity: Certified by/date: Certification Due: IH Report: 08-183 2) Certification records are to be maintained 5 years by SU HVAC or E&M. [NOTE: If a qualified contractor conducts the certification, the project manager must transfer certification records to the SU HVAC Shop or E&M, as appropriate.] For units that FAIL, immediately: 1) Inform users and facility manager the unit has FAILED performance inspection and may not be used until the unit has been certified. Post signage on gas cabinet. 2) Document that unit has failed performance inspection. 3) Repeat performance evaluation after an authorized repair/ maintenance personnel has been able to make necessary adjustments/ repairs.
Stanford University Gas Cabinet Certification Form Date: Technician/Company: Survey Equipment: Thermal anemometer Model # Unit # Last Date of Calibration Gas Cabinet Information Building, Room # Gas Cabinet Local ID Make/Model of Gas Cabinet Program ID # (assigned by Stanford) Fan System # 1. Qualitative Evaluation - Smoke Test: Smoke generated around face of perimeter contained? Y/N 2. Quantitative Evaluation - Velocity Measurements: Average Velocity (fpm): (or attach digital printout) Minimum Velocity (fpm) Accept (Y / N) Comments: 3. Equipment Inspection: Item Yes/No Comments Doors close and latch automatically? Y/N Self Closing Windows/Ports close automatically? Y/N 4. Overall Assessment: Gas Cabinet PASSES? Y/ N Comments: