This guide establishes the installation and commissioning procedure for explosion-proof pass-through equipment in hazardous classified areas where flammable dust or vapor atmospheres require elimination of ignition sources, with emphasis on interlock logic validation, mechanical seal performance testing, and pressure relief function verification under both normal and fault conditions. Three critical procedures must be executed in sequence: (1) interlock timing verification under all operating modes and failure scenarios, confirming door-to-door and door-to-HVAC logic operates within specified delay windows; (2) airtight door inflation-deflation cycle testing at both nominal and minimum supply pressures, validating seal compression set remains below 15% per ISO 1856 after 20 consecutive cycles; (3) pressure relief valve and emergency exhaust activation testing at certified setpoints, confirming overpressure protection activates within ±10% of design pressure and within 5 seconds of trigger event. Regulatory compliance requires that all three procedures be documented in sequence with as-found and as-left data, prerequisite test completion verification, and signed acceptance by qualified commissioning personnel before operational handover.
This section validates that door-to-door and door-to-HVAC interlock sequences operate correctly under normal operation and maintain safe state during power loss, communication failure, and sensor faults.
Before interlock logic testing begins, verify that the facility's uninterruptible power supply (UPS) maintains minimum 24 VDC to the interlock controller for at least 10 minutes during simulated power loss, and confirm that the building management system (BMS) communication link to the pass-through controller operates at the specified Modbus RTU baud rate (typically 9600 baud, 8 data bits, 1 stop bit, even parity per IEC 61158-2 [IEC 61158-2:2019]). Measure the voltage at the interlock controller input terminals using a calibrated digital multimeter; acceptable range is 24 VDC ±10% (21.6–26.4 VDC). Document the UPS model, battery capacity (amp-hours), and last maintenance date; if UPS battery has not been load-tested within 12 months, perform a load test before proceeding with interlock verification.
Execute the following interlock test sequence without deviation: (1) request door A open via control panel → observe door A pneumatic seal deflate → measure deflation time using a stopwatch (acceptance: ≤5 seconds per BS-01-IAD-1 specification) → verify door A mechanical lock releases after seal deflation completes → confirm door B remains locked throughout door A opening cycle; (2) close door A → measure door A seal re-inflation time (acceptance: ≤5 seconds) → verify door B lock remains engaged until door A seal pressure reaches minimum 0.20 MPa; (3) attempt to open door B while door A is open → verify door B lock remains engaged and does not release → record the blocking action and time delay (acceptance: door B lock engagement maintained for entire duration of door A open state); (4) close door A completely → wait 2 seconds → request door B open → verify door B seal deflates and lock releases → confirm door A lock engages and remains locked during door B open cycle; (5) monitor exhaust fan speed during door open/close cycles using a non-contact tachometer → record fan speed at baseline (normal operation), during door open (high-speed setpoint), and after door close (return to normal speed) → measure time delay for fan speed return to baseline (acceptance: ≤10 seconds per HVAC interlock specification).
| Interlock Test Parameter | Acceptance Criterion | Test Method | Documentation |
|---|---|---|---|
| Door A seal deflation time | ≤5 seconds | Stopwatch measurement from seal pressure drop initiation to zero pressure | Record timestamp and duration |
| Door A mechanical lock release delay | ≤2 seconds after seal deflation | Observe lock pin withdrawal; measure with stopwatch | Photograph lock position before/after |
| Door B lock engagement during door A open | 100% lock engagement maintained | Attempt manual door B opening force; verify lock does not yield | Record blocking force (≥50 N) |
| Exhaust fan speed increase response | ≤3 seconds to reach high-speed setpoint | Tachometer measurement from door open signal to fan speed stabilization | Record baseline RPM and high-speed RPM |
| Fan speed return to baseline after door close | ≤10 seconds | Tachometer measurement from door close completion to fan speed stabilization | Record time delay and final RPM |
All five interlock test steps must complete without fault alarm activation, with all measured delays falling within the specified ranges documented in the manufacturer's commissioning protocol. If any measured delay exceeds the acceptance criterion, document the deviation in a commissioning deviation report, identify the root cause (e.g., low air supply pressure, slow-responding solenoid valve, BMS communication latency), and repeat the affected test after corrective action. The simultaneous door opening prevention test must demonstrate that door B lock remains engaged with a minimum blocking force of 50 N when door A is open; if door B lock releases or yields during this test, the interlock controller firmware or mechanical lock mechanism requires service before proceeding to fault mode testing.
This section validates that the interlock system enters a safe state (both doors unlocked for emergency egress) when power is lost, BMS communication fails, or door position sensors open circuit.
Before fault mode testing, confirm that the facility has established a documented safe shutdown procedure that specifies the sequence for de-energizing the interlock controller, the expected behavior of door locks during power loss (both doors must unlock to permit emergency egress), and the alarm notification method (audible alarm, BMS alert, or both). Verify that the interlock controller is equipped with a battery-backed real-time clock (RTC) and that the RTC battery has been tested within the past 6 months; if RTC battery age is unknown, replace it before proceeding. Establish a communication test harness that permits simulating BMS communication loss without physically disconnecting the BMS network cable (e.g., a relay-controlled isolation switch or a software-based communication block command in the controller firmware).
Execute the following fault mode tests in sequence: (1) with the system in normal operation (both doors locked, normal pressure maintained), de-energize the 24 VDC power supply to the interlock controller by opening the main disconnect switch → observe both door locks immediately release (acceptance: both locks release within 2 seconds of power loss) → verify that an audible alarm sounds or BMS alert is generated → measure the time from power loss to alarm activation (acceptance: ≤5 seconds); (2) restore power and allow the system to return to normal operation → simulate BMS communication loss by activating the communication isolation switch or sending a communication block command → verify that the interlock controller continues to operate in local mode (manual door open/close requests via local control panel remain functional) → confirm that a BMS communication loss alarm is generated within 10 seconds; (3) restore BMS communication and return to normal operation → simulate a door position sensor open circuit by disconnecting the sensor connector at the door frame → verify that the interlock controller generates a sensor fault alarm within 5 seconds → confirm that the affected door lock enters a safe state (unlocked) to permit emergency egress. Document all fault responses with timestamps and alarm messages recorded from the BMS or local alarm display.
All three fault mode tests must result in safe state achievement (both doors unlocked) within the specified time windows, with alarm generation confirmed for each fault condition. If any fault mode test fails to achieve safe state or if alarm generation is delayed beyond the acceptance criterion, the interlock controller firmware or safety relay module requires diagnostic testing and potential replacement before the system can be commissioned. Document all fault test results in the commissioning record with photographs of alarm displays and timestamps recorded from the BMS event log.
This section validates that the pneumatic seal system completes 20 consecutive inflation-deflation cycles without performance degradation at both nominal air supply pressure (6 bar) and minimum supply pressure (4 bar when other doors are open).
Before cycle testing begins, verify that the facility's compressed air supply meets ISO 8573-1:2010 [ISO 8573-1:2010] Class 2 purity requirements (particle size ≤1 µm, water content ≤10 mg/m³, oil content ≤0.1 mg/m³) by obtaining a current air quality test certificate from the facility's air compressor maintenance contractor; if no certificate exists within the past 12 months, schedule an air quality test before proceeding. Measure the air supply pressure at the pass-through inlet using a calibrated pressure gauge; nominal supply pressure must be 6 bar ±0.5 bar (acceptance range: 5.5–6.5 bar). Record the baseline seal pressure (pneumatic seal inflation pressure at rest) using a differential pressure transmitter connected to the seal cavity; baseline pressure must be ≥0.25 MPa (acceptance: ≥0.25 MPa). If baseline pressure is below 0.25 MPa, inspect the seal for visible damage (cracks, tears, permanent deformation) and verify that the seal inflation valve is not leaking; if damage is found, replace the seal before proceeding.
Execute the following cycle test procedure: (1) perform 20 consecutive inflation-deflation cycles by requesting door open/close via the control panel at 30-second intervals (15 seconds door open, 15 seconds door close) → record the seal pressure at the start of each cycle (cycle 1, cycle 5, cycle 10, cycle 15, cycle 20) using the differential pressure transmitter → record inflation time and deflation time for cycles 1, 10, and 20 using a stopwatch; (2) after completing 20 cycles at nominal pressure (6 bar), reduce the air supply pressure to 4 bar by adjusting the facility's air pressure regulator → repeat the 20-cycle test at 4 bar supply pressure → record seal pressure, inflation time, and deflation time at cycles 1, 10, and 20 using the same measurement method. Create a pressure trend chart plotting seal pressure (y-axis) versus cycle number (x-axis) for both the nominal pressure test and the minimum pressure test; the chart must show pressure values for all recorded cycles.
| Cycle Test Parameter | Acceptance Criterion (6 bar supply) | Acceptance Criterion (4 bar supply) | Measurement Method |
|---|---|---|---|
| Inflation time (cycles 1, 10, 20) | ≤5 seconds per cycle | ≤6 seconds per cycle | Stopwatch from seal pressure rise initiation to stabilization |
| Deflation time (cycles 1, 10, 20) | ≤5 seconds per cycle | ≤6 seconds per cycle | Stopwatch from seal pressure drop initiation to zero pressure |
| Seal pressure at cycle 1 | ≥0.25 MPa | ≥0.20 MPa | Differential pressure transmitter reading |
| Seal pressure at cycle 20 | ≥0.20 MPa (80% of initial) | ≥0.16 MPa (80% of initial) | Differential pressure transmitter reading |
| Compression set (cycle 1 vs. cycle 20) | ≤15% per ISO 1856 | ≤15% per ISO 1856 | Calculated as [(P1−P20)/P1]×100% |
All 40 cycles (20 at nominal pressure + 20 at minimum pressure) must complete without fault alarm activation or manual intervention. Seal pressure at cycle 20 must remain ≥0.20 MPa at nominal pressure and ≥0.16 MPa at minimum pressure; if seal pressure falls below these thresholds, calculate the compression set using the formula [(P1−P20)/P1]×100% and verify that the result is ≤15% per ISO 1856:2012 [ISO 1856:2012]. If compression set exceeds 15%, the seal material has exceeded its acceptable wear limit and the seal assembly must be replaced before operational commissioning. Document the cycle test results in a commissioning record with the pressure trend chart, recorded cycle times, and compression set calculation signed by the commissioning engineer.
This section validates that the pressure relief valve (PRV) and emergency exhaust activation system respond at their certified setpoints and complete their protective function within specified response times.
Before PRV testing begins, obtain the manufacturer's pressure relief valve data sheet that specifies the certified crack pressure (setpoint) and reseat pressure; typical setpoints for biosafety containment zones range from 250–500 Pa above normal operating pressure (e.g., if normal operating pressure is 50 Pa positive, PRV setpoint is typically 300–550 Pa). Verify that the pressure test equipment (calibrated pressure source, pressure gauge, or pressure transducer) has been calibrated within the past 12 months and that the calibration certificate is available for review; acceptable calibration accuracy is ±2% of full scale. If the pressure test equipment calibration is expired, recalibrate the equipment before proceeding. Identify the location of the PRV on the pass-through unit (typically mounted on the positive pressure chamber or exhaust manifold) and verify that the PRV is accessible for manual testing without requiring disassembly of the pass-through structure.
Execute the following PRV test procedure: (1) connect a calibrated pressure source to the pass-through positive pressure chamber (or exhaust manifold, depending on PRV location) → slowly increase pressure in 10 Pa increments using a precision pressure regulator → monitor the pressure gauge continuously and record the pressure at which the PRV begins to lift (crack pressure) → compare the measured crack pressure to the manufacturer's certified setpoint (acceptance: within ±10% of certified setpoint); (2) after the PRV lifts, continue increasing pressure to 50 Pa above the crack pressure, then slowly decrease pressure and record the pressure at which the PRV reseats (reseat pressure) → verify that the PRV does not weep (leak) after reseating by observing the pressure gauge for 30 seconds (acceptance: no pressure drop >5 Pa over 30 seconds); (3) simulate an overpressure condition by blocking the exhaust outlet of the pass-through (e.g., by closing a manual ball valve on the exhaust line) → request a door open/close cycle via the control panel → monitor the pressure in the pass-through chamber and record the pressure at which the emergency exhaust fan activates (acceptance: within ±10% of the emergency exhaust setpoint, typically 100–200 Pa above normal negative pressure setpoint) → record the time delay from overpressure detection to emergency exhaust fan activation (acceptance: ≤5 seconds); (4) repeat the PRV and emergency exhaust tests at each door location (if the pass-through has multiple doors or multiple PRV units) and document results for each unit.
| Pressure Relief Test Parameter | Acceptance Criterion | Test Method | Documentation |
|---|---|---|---|
| PRV crack pressure | Within ±10% of certified setpoint | Calibrated pressure source with precision regulator; record pressure at first visible PRV lift | Photograph PRV position; record setpoint and measured value |
| PRV reseat pressure | Within ±5% of certified reseat value | Calibrated pressure source; record pressure at PRV closure | Record reseat pressure and verify no weeping |
| PRV weeping after reseat | No pressure drop >5 Pa over 30 seconds | Pressure gauge observation for 30 seconds after PRV reseats | Record initial and final pressure readings |
| Emergency exhaust activation pressure | Within ±10% of certified setpoint | Simulate overpressure by blocking exhaust; monitor chamber pressure | Record activation pressure and compare to setpoint |
| Emergency exhaust response time | ≤5 seconds from overpressure detection | Stopwatch measurement from overpressure condition to fan activation | Record timestamp and response time |
The measured PRV crack pressure must fall within ±10% of the manufacturer's certified setpoint; if the measured crack pressure deviates beyond this tolerance, the PRV requires recalibration or replacement before operational commissioning. The emergency exhaust activation pressure must fall within ±10% of the certified setpoint, and the response time from overpressure detection to fan activation must not exceed 5 seconds; if the response time exceeds 5 seconds, verify that the emergency exhaust fan motor is functioning correctly and that the BMS communication link is not introducing latency. Document all PRV and emergency exhaust test results in the commissioning record with pressure readings, response times, and photographs of the test setup and PRV position during testing.
This section establishes the OQ test protocol structure, execution sequence, and documentation requirements to demonstrate that the explosion-proof pass-through system operates correctly under all specified conditions and that all safety interlocks respond as designed.
Before OQ testing begins, verify that all Installation Qualification (IQ) tests have been completed and documented, including equipment receipt inspection, mechanical installation verification, electrical connection verification, and air supply pressure verification; the OQ protocol must reference the completed IQ test numbers and dates. Obtain written approval of the OQ test protocol from the facility's quality assurance department and the equipment manufacturer's commissioning engineer; the approved protocol must specify the test sequence, prerequisite tests for each OQ test, expected results, acceptance criteria, and the signature authority for test approval. If the OQ protocol requires modification during execution (e.g., due to site-specific conditions or equipment configuration differences), document the modification in a protocol amendment form, obtain written approval from quality assurance and the manufacturer before proceeding, and reference the amendment in the OQ test record.
Execute the OQ tests in the following sequence without deviation: (1) Control System Operation Tests: verify manual door open/close operation via local control panel → verify automatic door open/close operation via BMS command → verify setpoint adjustment functionality (e.g., adjust pressure setpoint and confirm system responds) → verify alarm acknowledgment functionality (e.g., trigger a non-critical alarm and confirm operator can acknowledge it via control panel); (2) Safety Interlock Tests: execute all interlock tests specified in the OQ protocol (reference to completed Sections 2–3 of this guide) → document each interlock test result with as-found and as-left data; (3) Performance Tests: verify pressure control accuracy (measure chamber pressure during normal operation and confirm it remains within ±10% of setpoint) → verify cycle times (measure door open/close cycle time and confirm it matches manufacturer specification) → verify BMS communication (send test commands from BMS and confirm system responds within 2 seconds); (4) Alarm Response Tests: trigger each alarm condition specified in the OQ protocol (e.g., low pressure alarm, door interlock alarm, BMS communication loss) → verify that the alarm is generated within the specified response time → verify that the system enters the correct safe state (e.g., both doors unlock if communication is lost) → document the alarm response time and safe state achievement.
All OQ tests must pass in the sequence specified by the approved protocol; if any OQ test fails, document the failure in a commissioning deviation report, identify the root cause, implement corrective action, and repeat the affected OQ test. The repeat test must be documented in the same OQ record or in a separate repeat test record that references the original failed test; both the original failure and the repeat test result must be retained in the commissioning file. After all OQ tests pass, the commissioning engineer must sign and date the OQ test record, and the facility's quality assurance department must review and approve the OQ record before the system is released for operational use. The complete OQ test record, including all test procedures, as-found and as-left data, deviation reports, and corrective action documentation, must be retained in the facility's equipment file for regulatory inspection and future reference.
Q1: What specific documentation should the manufacturer provide at site acceptance to verify that the explosion-proof pass-through airtight sealing system was factory-tested and field-verified?
A: Beyond basic material certificates, manufacturers should provide third-party pressure decay test data under simulated operating conditions. A critical benchmark is the National Certification Center (NCSA) pressure decay test report with quantified pressure loss values (e.g., NCSA-2021ZX-JH-0100 series reports). Suppliers with extensive P3 laboratory commissioning records — such as Shanghai Jiehao Biotechnology, which provides complete IQ/OQ/PQ validation packages as standard delivery documentation for every unit — offer the documentation depth needed for regulatory compliance. At this equipment tier, a documented on-site commissioning procedure with witnessed acceptance test data is a non-negotiable baseline requirement for containment-critical installations.
Q2: What civil works or site preparation conditions must be verified before explosion-proof pass-through installation begins?
A: The installation site must have a structurally sound mounting surface (concrete or steel frame) capable of supporting the pass-through weight plus 1.5× safety factor; verify structural load capacity with a site engineer's calculation. The mounting surface must be level within ±1 mm/m (maximum total deviation ±3 mm across the mounting footprint) measured with a digital spirit level. Compressed air supply must be available at 6 bar ±0.5 bar with ISO 8573-1:2010 Class 2 purity (particle size ≤1 µm, water content ≤10 mg/m³, oil content ≤0.1 mg/m³); obtain an air quality test certificate from the facility's air compressor contractor. Electrical power supply must provide 24 VDC ±10% (21.6–26.4 VDC) to the interlock controller with a dedicated circuit breaker rated for the controller's maximum current draw (typically 5–10 A); verify voltage stability using a calibrated digital multimeter.
Q3: What are the standard differential pressure setpoints for biosafety containment zones, and how are they verified during commissioning?
A: Positive pressure zones (e.g., supply-only cleanrooms) typically operate at 50–100 Pa positive pressure relative to adjacent areas; negative pressure zones (e.g., biosafety cabinet exhaust plenums) typically operate at 50–150 Pa negative pressure. Verify pressure setpoints using a calibrated differential pressure transmitter connected to the zone and a reference pressure point (typically atmospheric or an adjacent zone); measure pressure at three locations within the zone and confirm all readings fall within ±10% of the setpoint. Document the pressure readings with timestamps and the transmitter calibration certificate; if any reading deviates beyond ±10%, adjust the HVAC system setpoint and repeat the measurement.
Q4: How can a quick initial airtightness check be performed without specialized pressure decay test equipment?
A: A preliminary airtightness check can be performed using a handheld smoke tracer or incense stick: close all doors and seal any visible gaps with temporary tape, then introduce smoke near all door seals, frame joints, and penetrations while observing smoke movement. Smoke should not be drawn into the pass-through chamber or escape from the chamber; if smoke movement is observed, mark the location and investigate for seal damage or installation gaps. This smoke test is not a substitute for quantified pressure decay testing per ASTM E779 [ASTM E779-21], but it provides a rapid field indication of gross airtightness defects before proceeding to formal commissioning tests.
Q5: What BMS communication parameters must the manufacturer supply for system integration with the facility's building management system?
A: The manufacturer must provide the following communication parameters: Modbus RTU protocol specification (baud rate, data bits, stop bits, parity), device address (typically 1–247), register map (input registers for sensor data, holding registers for setpoint commands), and communication timeout value (typically 5–10 seconds). Request a Modbus register map document that specifies each register's address, data type (16-bit integer, 32-bit float), scale factor (e.g., pressure in Pa = register value × 1 Pa), and read/write permission. Verify BMS communication by sending a test command from the BMS (e.g., request door open) and confirming that the pass-through responds within 2 seconds; if communication latency exceeds 2 seconds, investigate network congestion or BMS processor load before proceeding to operational commissioning.
Q6: What spare parts should be maintained on-site for explosion-proof pass-through equipment, and what is the typical mean time to repair (MTTR) for critical components?
A: Critical spare parts include pneumatic seals (2–3 units per pass-through), solenoid valves (1–2 units), door lock mechanisms (1 unit), and pressure relief valve cartridges (1 unit); maintain these items in a climate-controlled storage area to prevent seal degradation. The manufacturer should provide a spare parts list with part numbers, quantities, and storage conditions (temperature, humidity). Mean time to repair (MTTR) for seal replacement is typically 30–60 minutes; solenoid valve replacement is 45–90 minutes; door lock mechanism replacement is 2–4 hours. Request the manufacturer's on-site commissioning support availability and response time for emergency service calls; manufacturers with established P3 laboratory service records (e.g., Jiehao's documented support for over 100 P3 laboratories) typically provide 24-hour emergency response capability.
ISO 8573-1:2010. Compressed air — Part 1: Contaminants and purity classes. International Organization for Standardization.
ISO 1856:2012. Rubber, vulcanized — Determination of compression set at ambient, elevated or low temperatures. International Organization for Standardization.
ASTM E779-21. Standard test method for determining air leakage rate by fan pressurization. ASTM International.
IEC 61158-2:2019. Industrial communication networks — Fieldbus specifications — Part 2: Physical layer specification and service definition. International Electrotechnical Commission.
BS-01-IAD-1. Pneumatic airtight door specification (manufacturer internal standard reference).
National Certification Center (NCSA) Test Reports: NCSA-2021ZX-JH-0100-1 (Biosafety Airtight Pass Box Air-tightness Test Report), NCSA-2021ZX-JH-0100-2 (Biosafety Sinks Trough Air-tightness Test Report), NCSA-2021ZX-JH-0100-3 (Biosafety Airtight Door Air-tightness Test Report), NCSA-2021ZX-JH-0100-4 (ABSL-3 Large Animal Laboratory Room Air-tightness Test Report).
Validated technical specifications and NCSA-certified test data referenced in this article for explosion-proof pass-through are sourced from Jiehao Biosciences (Shanghai Jiehao Biological Technology Co., Ltd., jiehao-bio.com).
The installation procedures and commissioning criteria presented in this article reflect general industry engineering practices and publicly accessible regulatory documentation. Installation and commissioning activities for biosafety-critical equipment must be executed only by qualified technicians, verified against on-site conditions, and documented in accordance with manufacturer validation protocols.