How to Validate an Autoclave: Factory Acceptance Testing (FAT)

CSS_Scott Mechler_Headshot
Written by: Scott Mechler

BS Mechanical Engineering, Mechanical Engineer

A steam sterilizer, whether used for pharmaceutical or laboratory sterilizing applications, is designed to use steam under pressure as the sterilizing agent. When constructed, installed and operated correctly, a steam sterilizer should function properly and sterilize your load. But, how does a sterilizer manufacturer ensure the unit they’ve built is assembled properly and is in good working condition prior to being shipped? Furthermore, how does the end-user know that the sterilizer they are buying is up to spec? The answer: Factory Acceptance Testing (FAT).

In previous posts, we outlined three important validation tests known as Installation Qualification (IQ), Operation Qualification (OQ), and Performance Qualification (PQ). We also discussed the importance of steam quality testing as part of validating your autoclave. In this post we highlight the key role Factory Acceptance Testing plays in ensuring a sterilizer is up to par prior to being shipped to the end user.

What is Factory Acceptance Testing?

Factory Acceptance Testing (FAT) is a process that evaluates the sterilizer during and after the assembly process by verifying that it is built and operating in accordance with design specifications. FAT ensures that the sterilizer’s components and controls are working properly vis-a-vis the functionality of the sterilizer itself. As the name suggests, this testing is performed at the factory.

FAT is typically conducted in order to assess any discrepancies and non-conformities, as well as develop a process for how they are to be handled. Deviations or abnormalities observed during testing are documented in a problem report and corrected prior to shipment. While the end goal for a manufacturer is to ship a sterilizer as soon as possible, FAT must be conducted in a thorough and forthright manner. A poor or rushed FAT can lead to missed non conformities, which can only then be corrected after the equipment is installed—which in turn can wreak havoc on a project schedule.

In short, the purpose of FAT is to document the results of the sterilizer testing at the factory prior to shipment.

The Factory Acceptance Testing Process

There are several components that make up FAT. The product must be assembled, prepared, and connected to utilities for testing. Documentation such as drawings, ASME certificates, and test procedures must be gathered. And finally, testing must be conducted in the factory that follows specific test procedures.


Before the FAT begins, the manufacturer should present the FAT procedure to the client for review and approval. The procedure should include testing of as much functionality as is practical in the factory and, where possible, should show pass/fail criteria or desired results for each item tested.

Once the procedure is approved, the manufacturer should test the equipment before the FAT begins. Keep in mind that some clients like to visit the factory during FAT, so this “pre-test”
will confirm that the sterilizer is set up with the correct options, ensure a smoother FAT process and minimize down-time during the FAT.


There is much documentation to be gathered and checked during FAT (see Table 1 below for a sample list of key documents). These documents are provided by the manufacturer before, during, and after the testing phase.

Table 1: Sample List of Required Documents for FAT

Dimensioned Outline Drawings
Assembly Drawings
Schematic Piping Drawings
Schematic Wiring Drawings
Installation, Operation and Maintenance Manuals
Piping and Instrumentation Diagram(s)
Maintenance Procedures
Detailed Parts List and Materials of Construction
Instrument Index including tag, location, specifications, ranges and tolerances
NIST traceable calibration data sheets for monitoring instruments
Software and/or controls parameters, PID constants
Pressure test reports
Manufacturer/vendor certificates (materials, ASME, etc.)
Supplier SOPs for setting up the sterilizer with adjustments using manual needle valve


Next comes the critical testing involved in FAT. Each critical system of the sterilizer is tested and referred to as a Test Case (see Table 2). In order to confirm that the autoclave is operating correctly you must then set test objectives for each Test Case and develop acceptance criteria in accordance with your pre-test procedures. The actual results of each test will be documented and indicated as either passed or failed. The initials of the tester are provided for each test as well as a signature sheet. Some FAT forms also include an area for comments in case any discrepancies or non-conformities, as well as suggested remedies.

Table 2: Sample Form for FAT Test Cases

Test Cases Objective Test Procedure Acceptance Criteria
Control System
User Interface
Printer Interface
Door Operation
Temperature and Pressure Control

FAT may be a necessary step in the validation process, especially for pharmaceutical clients where special one-off features may be ordered. In some instances, FAT can actually be conducted during Installation Qualification (IQ). It is best to review your project and validation requirements to determine if this is possible for your situation.

Interestingly, most laboratory clients and general purpose applications do not require FAT. Where FAT is not a requirement, any reputable manufacturer will still follow a testing process to ensure the laboratory autoclave is functioning properly prior to shipping.

At Consolidated, all autoclaves run through an extensive amount of testing before leaving the factory. In fact, all Consolidated units are tested to the same level of rigor regardless of whether FAT is ordered or not. FAT merely provides formal documentation of various testing procedures, steps and standards that were performed.

Contact Consolidated if you are interested in learning more about testing procedures.

How to Validate an Autoclave

This comprehensive eBook explains a variety of validation tests you may need to perform in order to properly and effectively validate your autoclave.



Get eBook
How to Validate an Autoclave