In sterile environments, including pharmaceutical manufacturing, food & beverage production and biotechnology, pressure gauges must undergo rigorous cleaning and sterilization to ensure hygienic compliance while maintaining process integrity and operational safety.
Ashcroft is a globally recognized leader in pressure and temperature instrumentation. As experts in this field, it is our job to fully understand the requirements our products must meet for use in these highly regulated industries and answer customer questions to help them make informed decisions.
The question that prompted this article was from a customer who wanted to know the different ways to keep their pressure instruments compliant with hygienic requirements. Read this article to learn what hygienic compliance means for sterile processes, who sets and enforces these standards and how three widely used cleaning methods—Clean-in-Place (CIP), Sterilize-in-Place (SIP) and autoclaving can help your systems prevent contamination.
When you are done, you will have a better understanding of these processes, applications, benefits, and limitations as they relate to sanitary operations. You will also be directed to additional resources that can help you determine which instruments are best suited to keep your system running safely and efficiently in sterile environments.
Who sets the requirements for pressure instruments used in sterile environments?
The U.S. Food and Drug Administration (FDA) establishes and enforces stringent cleaning and sterilization standards for the pharmaceutical, biotech and food and beverage industries under current Good Manufacturing Practices (cGMP). To ensure manufacturing processes remain free from contamination, manufacturers must follow specific protocols for eliminating microorganisms, safeguarding product quality and ensuring consumer safety.
Sanitary design standards for pressure gauges and pressure sensors across all three industries often adhere to 3-A Sanitary Standards. EN 10205: 2004 3.1 compliance is monitored through material tracability documents, audits, inspections, licensing, and potential enforcement actions such as recalls and facility shutdowns.
Among the most common methods for maintaining hygienic environments are Clean-in-Place (CIP), Sterilize-in-Place (SIP), and autoclaving. While they all serve important sanitation functions, each has a unique purpose and application. Understanding their differences and uses is essential for ensuring compliance and maintaining product integrity. Let's take a closer look at each.
Clean-in-Place (CIP): automated internal cleaning without disassembly
CIP is a fully automated, repeatable cleaning method that uses water, detergents and sometimes sanitizers (or steam) to clean the internal surfaces of process equipment without the need to take them apart. This approach is a favorite in industries where equipment needs to be cleaned frequently to avoid any cross-contamination. For example, in food and beverage operations, residues and deposits from the production process can accumulate in tanks, piping, and other areas, leading to the growth of harmful microorganisms that regular cleaning and disinfection processes may miss.
CIP is ideal for use when frequent cleaning (not sterilization) is required for internal surfaces between production runs, equipment cannot be disassembled and you need an automated and repeatable process.
Typical CIP automated process
1. Pre-rinse: flushes out bulk residue using water.
2. Detergent wash: adds a cleaning agent (alkaline or acid-based) to remove soils, biofilms, fats, or proteins.
3. Intermediate rinse: removes detergent and any loosened soil.
4. Final rinse/sanitization: may use water-for-injection (WFI), sanitizers, or Sterilize-in-Place (SIP) with steam.
Benefits of CIP
- Repeatable & validated cleaning to ensure regulatory compliance
- Reduced downtime because it doesn't require dismantling
- Enhanced operator safety due to less exposure to cleaning chemicals
- Consistent product quality by preventing cross-contamination
- Data integrity with automated recordkeeping and audit trails
Sterilize-in-Place (SIP): microbial decontamination with steam
Once a system has been thoroughly cleaned using Clean-in-Place (CIP), which removes visible residues like product buildup and mineral deposits, it is still not considered sterile. This is where Sterilize-in-Place (SIP) comes into play. SIP uses pressurized steam to kill microorganisms, including bacteria, viruses, fungi, and spores that may remain after cleaning. The goal is to achieve a validated sterility assurance level (SAL) that meets regulatory standards.
Typical SIP process
- Activate steam supply. Sterile, saturated steam is introduced into the system, typically generated from purified water sources that must meet clean steam quality standards.
- Remove air. Air inside the system is displaced by steam, either passively or with vacuum assistance. Pockets of air can prevent steam from making contact with surfaces, resulting in incomplete sterilization.
- Heat. The internal surfaces of the equipment are gradually brought to sterilization temperature—typically 121 °C (250 °F) or higher, sometimes reaching up to 135 °C (275 °F) for more rigorous applications.
- Hold. When target temperature is reached, the system is held at that temperature for a pre-determined time period depending on the complexity and load of the system. During this phase, steam thoroughly contacts all internal surfaces, ensuring even the most resistant microorganisms (such as spores) are destroyed.
- Monitor and control. Temperature, pressure and exposure time are continuously monitored and documented, often through PLC (programmable logic controller) systems. Any deviation from validated conditions may require the cycle to be repeated.
- Cool and dry. After the cycle is complete, the system is slowly depressurized and cooled. In some setups, sterile air or nitrogen is introduced to aid drying and prevent vacuum formation.
- Post-sterilization integrity check. Filters, valves, and other components may be tested for integrity. In pharmaceutical and biotech settings, biological indicators or chemical integrators may be used to validate the effectiveness of the sterilization cycle.
Benefits of SIP
- Validated sterilization process that meets regulatory requirements for aseptic manufacturing
- High-level microbial inactivation, including spores, to ensure sterility assurance
- No disassembly required, reducing system exposure and contamination risk
- Automated control of temperature, pressure and time for consistent sterilization outcomes
- Compatible with closed systems, maintaining sterile integrity from cleaning through production
- Minimized human intervention, enhancing both safety and reproducibility
- Sterile steam leaves no chemical residue, eliminating risk of product contamination
Autoclaving: external component sterilization through high-pressure steam
An autoclave is a sealed, pressurized chamber designed to sterilize manufacturing equipment, instruments and tools by exposing them to high-pressure saturated steam. This standalone sterilization method uses a combination of elevated temperature and pressure to ensure the destruction of bacteria, viruses, fungi, and even the most resistant microbial forms—spores.
Unlike CIP and SIP, which clean or sterilize fixed internal process systems, autoclaves are used for items that can be loaded into the chamber. It is considered one of the most effective and reliable sterilization techniques and is widely used in healthcare, laboratories and manufacturing industries.
Typical autoclave process
- Load the Chamber. Items to be sterilized—such as instruments, labware, or sealed containers—are carefully arranged inside the autoclave to allow for even steam penetration. You will want to avoid overloading to prevent cold spots where sterilization may be incomplete.
- Remove air. The chamber is purged of air pockets that can act as thermal insulators and prevent sterilization. This is often done using gravity displacement (using steam to push out air through a vent) or with a pre-vacuum cycle (using a vacuum pump to remove air before steam is introduced).
- Inject steam. Saturated steam is introduced into the chamber, reaching a pressure typically around 15 psi (pounds per square inch) and a temperature of 121 °C (250 °F) or higher. The pressure raises the boiling point of water, allowing steam to remain in a hot, moist state that effectively kills microbes.
- Hold time. The autoclave maintains the set temperature and pressure for a defined period—usually 15 to 30 minutes, depending on the load and material type. This ensures even heat distribution and thorough sterilization throughout all items.
- Cool and depressurize. After the hold time, steam is vented and the chamber is slowly depressurized. The load is allowed to cool before removal to prevent condensation or thermal shock.
- Dry (optional). Some autoclaves include a drying cycle that uses vacuum or heated air to remove residual moisture, particularly for wrapped instruments or porous loads.
Choosing the right cleaning method for pressure gauges
Selecting the right cleaning method for your application depends on the level of cleanliness or sterility required, the design of the process system and the regulatory standards of the industry. As critical process instruments, pressure gauges and sensors must be maintained with the same care as any product-contact surface to ensure accurate readings and compliance with hygiene standards. Here is a guideline to follow:
- CIP is ideal when frequent cleaning is required and disassembly is impractical. It maintains a hygienic baseline but may not meet sterility requirements on its own.
- SIP should be used in conjunction with CIP when sterility is essential—especially in pharmaceutical manufacturing, where regulatory demands are stringent.
- Autoclaving is best suited for removable pressure gauges or components that can be separately sterilized, especially in lab or clinical settings.
Ready to learn more?
Now that you have more information about the different pressure gauge cleaning methods, we understand you may have more questions. Here are a few articles that may be of interest to you.
-
Best Pressure Instruments for Pharmaceutical and Biotechnology Applications?
- Considerations for Choosing a Sanitary Pressure Gauge
- Cleaning for Oxygen Service
- How Do I Select the Right Pressure Gauge Range?
Contact us to speak with one of our industry experts who can answer other pressure gauge questions. In the meantime, download our guide to learn more.
