Home » Pass Thru Interlock – Selecting the Right Pass through

Pass Thru Interlock – Selecting the Right Pass through

Pass Thru interlock - Hospital Operating Room and USP 800 Pharmacy Cabinets and Chambers with interlock and sealed doors

Selecting the Right Pass Through Interlock

Pass Thru Electronic Interlock is the Best Practice for Pass Through Cabinets and Chambers for USP 800 and 797! It is strongly recommends the retrofit of these types of pass-throughs with interlocking doors. Interlock ensures that inside and outside doors may never be opened simultaneously. Pass-thru cabinets (also called pass-thru airlocks) prevent contamination and increase productivity. Pass-thrus used in compounding pharmacies, must comply with USP 797 and USP 800, which stipulate interlock  requirements. 

USP General Chapter <800> Hazardous Drugs – Handling in Healthcare Settings defines Pass-through as ” An enclosure with interlocking doors that is positioned between two spaces for the purpose of reducing particulate transfer while moving materials from one space to another.”1

How Pass Through Interlocking Doors Work

Pass-thru cabinet doors for pharmacy and OR  installations, are designed with interlocks, so that only one side door can be opened at a time, which also prevents depressurization of the cleanroom, pharmacy or Operating Room. When materials and supplies are transferred a clinician  opens the pass-thru door on the “dirty air” side; the interlock mechanism automatically locks the “cleanroom” side door shut. The medical professional places materials into the pass-thru on the “dirty” side and closes  the door. The passthru’s interlocking doors on both sides tightly compress  to prevent air loss from the cleanroom. Now, the interlocking system will release, so the clinician can open the cleanroom-side door and transfer the materials and supplies  into the cleanroom. When the transfer is completed, the cleanroom side door is closed. When both doors are closed, the interlock is released and the pass-thru is ready for another use.

Learn More about CMP Pass Through Cabinets / Chambers

Pass Through with Interlock for hospital pharmacy detailed architectural drawing by Continental Metal Products

Mechanical Pass Thru Interlock

Mechanical interlock is designed with latch pins or rods. These latch pins typically resist up to 200 pounds of force. Typically these chambers are latched together using a manual means such as an outside latch, which a hospital professional latches to hold the two enclosure units together. An enclosure includes a back enclosure unit, a front enclosure unit hinged to the back enclosure unit, a rod coupled to the front enclosure unit, and a spring latch coupled to the back enclosure unit. The rod engages the spring latch when the front enclosure unit is closed upon the back enclosure unit. These mechanism do not securely hold a larger door tightly across the entire surface opening and there can be a rocking effect. There is a need for  a better, more secure method of latching the two interlocked doors.

Heavy Duty Pass-Through with Interlocking Doors

Pass Throughs with Interlocking Doors are a base line requirement of USP 800 and USP 797. Continental Metal Products exclusively offers an  Electronic Interlock System that locks the opposing doors in our Pass Through Cabinets. CMP utilizes a circuit board controller that is far more reliable than mechanical style systems.  

ISO Class 7 buffer room with an ISO class 7 ante-room:

USP General Chapter notes,”sterile compounding must follow standards in USP ,797.

A method to transport HDs, HD CSPs, and HD waste into and out of the negative pressure buffer room to minimize the spread of HD contamination. This may be accomplished by use of a pass-through chamber between the negative-pressure buffer area and adjacent space. The pass-through chamber must be included in the facility’s certification to ensure that particles are not compromising the air quality of the negative-pressure buffer room.” 2


500 lbs. of Force Resisted by Pass Thru Interlock

The interlocked door cannot be forced open. CMP’s exclusive system’s strength, resists up to 500 lbs. of force.  These double interlocked doors  maintain air pressure differentials. Supplies are easily transferred from the sterile core to the operating room, as well as through the compounding pharmacy.


CMP’s Pass Thru Interlock Cabinets / Chambers meet USP requirements because our Electronic Interlock System utilizes updated, state-of-the-art technology . This newest generation design insures increased operational functionality versus older generation mechanical interlock systems,.  The opposing immediately door locks with a  fail-safe design, providing a more secure seal. Mechanically interlocked doors do not hold as firmly and securely. 

The pass-through chambers minimize the need for movement between working areas and Buffer rooms, Chemo, and IV in Hospital Pharmacy Anteroom.

Extensive Available Options

CMP’s engineers are continuing to add more and more features and options to our pass through cabinets to meet hospitals changing requirements. 

Newer Options Include;

Wide Variety of Sizes of Pass Through Cabinets and Chambers

Continental Metal Products designs and manufactures the largest product line of Pass Through Cabinets, Chambers and Boxes to meet both USP Pharmacy 800 / 797, as wells all Hospital, Ambulatory Surgery Center,  Military Dental Surgery Clinics and Veterinary Clinic’s Operating Room requirements.

  • New Small Size Pass Through Chamber  18″x 18″, 24″ X 24″ size and 24″ w x 36″ h to meet limited space requirements     Small Pass Through Chamber with interlocking doors measuring 24" w x 24"H with Glass doors

Contact CMP to learn more.

Contact CMP for More Information
1,2 USP General Chapter <800> Hazardous Drugs – Handling in Healthcare Settings Links For Supplemental Resources „ Information on USP General Chapter <800> „ USP General Chapter <800> FAQs „ USP General Chapter <800> Education Courses „ This text is a courtesy copy of General Chapter <800> Hazardous Drugs – Handling in Healthcare Settings, intended to be used as an informational tool and resource only. Please refer to the current edition of the USP-NF for official text. This chapter alone is not sufficient for a comprehensive approach to safe handling of hazardous drugs. Additional chapters are required for complete implementation; see USP Compounding Compendium or USP-NF. 2017 Reprinted from USP 40—NF 35, Second Supplement (2017)