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Acronyms and abbreviations are commonly used with process analytics measurements found in the biopharma industry. This glossary is an attempt to de-code some of the more frequently used acronyms.


AgCl - Silver Chloride. Silver chloride is found in the reference and measurement electrodes within a pH sensor.

ANSI - American National Standards Institute. A non-profit organization that helps develop standards used in industrial equipment. Hamilton Retractex housing have optional ANSI flanges to ensure proper mounting.

API - Active Pharmaceutical Ingredient. The substance within the pharmaceutical end-product that directly affects the prevention or treatment of the disease.

APE - APplication Engineering. Hamilton offers a full line of off-the-shelf and Customized Products. E-mail [email protected] for support.

ATEX - ATEX is a European directive for electrical and mechanical equipment used in potentially hazardous areas. Products bearing the ATEX marking will have undergone testing for usage in the specific atmosphere. ATEX is a shortened abbreviation for ATmosphere EXplosible.


BNC - A type of electrical connector used with coaxial cable. BNC connectors are commonly found on pH sensors and some brands of bioreactor controllers.

BT - Bluetooth. This is the main wireless communication protocol used with Arc sensors.

BZ - Bonaduz, Switzerland. Our engineering and manufacturing site for Process Analytics sensors.


CDMO - Contract Development and Manufacturing Organization. These businesses partner with molecule inventor to assist in design, scale-up and eventual manufacturing of the end product.

CHO - Chinese Hamster Ovary cells. CHO cells are very common in mammalian cell culture applications. They are frequently used due to their robust tolerance of fluctuating pH, DO, temperature and pressure, as well as their well-known genome and their high yield potential.

CIP - Clean In Place. A common method of cleaning vessels and related piping after a batch. Typically a flush with a weak acid followed by a flush with a weak base are used to remove possible contaminants from the insides of the process hardware. A rinse cycle is performed after each flushing with acid / base.

COA - Certificate of Analysis. This is a quality document typically provided with liquid solutions. The COA provides batch specific information on the composition of the liquid.

CQA - Critical Quality Attributes. Per the FDA "A CQA is a physical, chemical, biological, or microbiological property or characteristic that should be within an appropriate limit, range, or distribution to ensure the desired product quality". The measurement of CPP help determine if the CQA is acceptable.

CPP - Critical Process Parameter. CPP is a pharmaceutical term for specific attributes that must be monitored within a process to ensure overall product quality. Normally a CPP has a specific tolerance that must be kept within the acceptable range to validate a production run. Examples of CPP could include pH or dissolved oxygen.


DI Water - Abbreviation for deionized water. DI water is purified water where all cation and anion molecules have been removed. Typically DI water is created through methods such as reverse osmosis, ultrafiltration or exposure to ion exchange resins.

DN - Diameter Nominal. This term is normally used with metric piping and flange dimensions that conform to ISO 6708 standards. DN flanges are options found with the Hamilton Retractex housing.

DO - Dissolved Oxygen. Gas phase oxygen is soluble in most liquids. Measurement of dissolved oxygen is frequently required to determine the suitability of the liquid for ongoing growth of organisms in the liquid. In other applications such as brewing, dissolved oxygen may be seen as contaminant thus is monitored to ensure product quality.

dCO2 - Dissolved Carbon Dioxide. Gas phase carbon dioxide is soluble in most liquids. Maintaining appropriate levels of dCO2 is critical to optimize cell respiration and overall cell growth.

DOQ - Declaration Of Quality (Hamilton Acronym). This is the final test document for a sensor. It includes specific information such as the serial number, lot number, date of manufacture, and final test data to verify the sensor meets specifications. This document is provided with each sensor within the packaging or can be accessed through the Hamilton website.


EDO - Electrochemical Dissolved Oxygen (Hamilton Acronym). Normally referring to Hamilton Polarographic Dissolved Oxygen Sensors

ECS - Electro-Chemical Signal (Hamilton Acronym). Commonly used with optical dissolved oxygen sensors that generate an output signal that mimics existing polarographic dissolved oxygen sensors. This is normally a nano-amp signal.

EHEDG - European Hygienic Engineering & Design Group. A non-profit organization that focuses on the sanitary requirements of food manufacturing. Hamilton sensors that have EHEDG certification have been evaluated for their hygienic design.

EMA - European Medicines Agency. The EMA is part of the European Union with the task of promoting and protecting human and animal health. The EMA is often seen as the equivalent of the US-Based Food and Drug Administration (FDA).

EPDM - Ethylene Propylene Diene Monomer. EPDM is a synthetic elastomer material commonly used for o-rings and other seals. It displays good chemical resistance and is considered biocompatible, meeting the requirements of USP Class VI and FDA CFR Title 21, section 177.2600.


FAT - Factory Acceptance Testing. A factory acceptance test is generally performed on-site at the manufacturer prior to shipment to the end user. FAT involves agreement between the vendor and end user about the testing to be performed, review of documentation related to the product, and finally actual testing of said product. FAT testing is most commonly performed on complex capital equipment purchases such as custom skids.

FDA - Food and Drug Administration. The FDA is a federal agency of the US government. It promotes public health through the development and enforcement of various regulations for the food, beverage, pharmaceutical, and medical industries.

FKM - A generic name for a family of fluorocarbon based elastomer materials. FKM is most commonly used for o-ring and seals and has good chemical resistance. Viton is the most common trade name of FKM. NOTE - FKM and FPM are similar acronyms for products from this same family.

FFKM - A generic name for a family of perfluoroelastomeric based elastomer materials. In general, FFKM is similar to FKM but contains a higher concentration of fluorine molecules. FFKM is known for its excellent chemical resistance and resistance to high temperatures. It is most commonly found in o-rings used in Hamilton products. Kalrez is a common trade name for FFKM. Also FFPM may also be used to designate these products.


G 1-¼ - this designation refers to a threaded connection commonly found on 25mm sockets used as a port on biopharma vessels such as bioreactors. Hamilton products such as FlexiFit static holders use a union nut with female G1-/4 threads to mate up with the socket on the vessel. The threads themselves are not wetted by the process but rely upon an o-ring seal against the internal diameter of the socket.

GMP - Good Manufacturing Practice. This is a frequently used term in biopharma production. GMP is promoted by regulatory agencies such as the FDA (Food and Drug Administration) to ensure that products are made in a consistent, safe manner. GMP is a broad term that encompasses best practices for documentation, sanitation, training, and validation. While GMP provides guidelines, it is up to the individual manufacturer to determine specific parameters for their processes. Also referred to as “cGMP” which stands for “current Good Manufacturing Practice”.


H - H Glass. A type of pH glass membrane known for good general chemical resistance. Most commonly used on the Polilyte Plus pH sensor family.

HART - Highway Addressable Remote Transducer. HART is a communication protocol that allows digital communication over the 4-20mA analog signal commonly used with industrial transmitters and sensors. HART communication was developed by Emerson in the late 1980s. HART protocol is available on Hamilton VisiFerm mA and VisiTrace mA optical dissolved oxygen sensors.

HB - HB Glass. A type of pH glass membrane known for good resistance to the effects of CIP cleaning. Most commonly used on the EasyFerm Bio pH sensor family.

HF - HF Glass. A type of pH glass membrane known for good resistance to the etching effects of Hydrofluoric Acid. Most commonly used on the Polilyte Plus pH sensor family.

HMI - Human Machine Interface. The HMI is screen or display of a controller, transmitter, or other device. Inputs may be performed using a keyboard, push buttons, or a touch screen.


IL - Insertion length (Hamilton Acronym). A common measurement found on sensor holders. IL refers to the length from a mounting flange (example - TriClamp) to the tip of the fitting. Insertion length is needed to understand how far a holder or sensor would protrude into a vessel.

IQ - Installation Qualification. IQ is verification of the proper installation and configuration of the equipment from the manufacturer. For Hamilton sensors IQ would involve verifying the physical installation of the sensor, review of accessories such as cables or wireless adapters, checking the wiring and power for the sensor, and finally reviewing the configuration of the sensor through ArcAir software.


K8 - K8/K9 Connectors are typically used on traditional pH / ORP sensors which lack temperature compensation. These connectors have a two pole design consisting of the center core and outer metallic threaded connection.

KCl - KCl is potassium chloride. Potassium chloride is the active component in the electrolyte used in glass membrane pH sensors.

kGy - Abbreviation for kilogray, a unit of radiation dose. Gamma radiation is used for sterilization of single use bioprocessing equipment. Hamilton single use sensors have a suggested range for minimum and maximum kGy to ensure their sterilization.

KLa - KLa refers to the mass transfer coefficient of oxygen. This coefficient is dependent on the design features of the bioreactor. Gas flow rate, stirrer design and speed, and sparger type will all impact KLa. In general, as a biopharma process is scaled up from R&D to pilot to production, keeping the KLa constant insures predictable yield.


LEVP - LEVP is a combination of several acronyms. LE refers to Liquid Earth. VP refers to the Variopin electrical connector commonly used on sensors. Hamilton pH sensors with LEVP will have an additional internal contact that is used to perform various diagnostics checks such as glass impedance to verify the health of the sensor.


M12 - M12 is a reference to circular electrical connectors commonly used for industrial sensor and cable connections. The external thread diameter is 12mm. M12 connectors can have from 3 to 12 contact pins. M12 connections may be male or female. They have a specific key / notch connect referred to as either a-code or b-code. All Hamilton VisiFerm mA and VisiTrace mA sensors use M12 connections.

mAb - monoclonal antibodies. These man-made proteins mimic the antibodies produced within the human body to target specific antigens found on foreign cells.

MFC - Mass Flow Controller. A device that measures and controls gas flow rate. In bioreactor applications these devices are used to measure the flow of oxygen and CO2 to the vessel.

MIR - Mid-Infrared. This region of the spectrum consists of 2 to 20 um wavelength infrared light. It is used for spectroscopy measurements of specific analytes such as CO2.


N5 (Surface Finish) - N5 is a surface finish grading common with many Hamilton sensors. The terminology comes from the ISO 1302 standard. N grading with higher numbers equate to rougher surfaces while N grading with lower numbers are smoother surfaces. N5 surface grading cross reference is shown below.

ISO 1302
Roughness Grade
micrometer (µm)
microinch (µin.)

N5.0 (Nitrogen) - Ultra high purity Nitrogen (99.999%). The 5 in the number refers to the number of 9's present in the purity rating. N5.0 Nitrogen is recommended for zero point calibration of Hamilton dissolved oxygen sensors..

nA - Nanoampere = 1 Amp * 10-9. Traditional polarographic dissolved oxygen sensors generate a weak nA current which is read by the transmitter or controller.

NIR- Near Infrared (from 780 nm to 2500 nm). This is a range that is used in various spectroscopy measurements.

NPT - American National Standard Pipe Thread standards, often called national pipe thread standards for short, are U.S. national technical standards for tapered screw threads used on threaded pipes and pipe fittings. NPT is defined by ANSI/ASME standard B1.20.1 : The taper rate for all NPT threads is 1 inch of diameter in 16 inches of length (3⁄4 inch per foot or 62.5 millimeters per meter) measured by the change of diameter (of the pipe thread) over distance of thread.

NTC - Negative Temperature Coefficient thermistors are non-linear resistors, which alter their resistance characteristics with temperature. The resistance of NTC will decrease as the temperature increases. NTC temperature elements are only found in Hamilton Arc sensors.


ODO - (Hamilton Acronym) Optical Dissolved Oxygen

OP - (Hamilton Acronym) O-ring Position. OP is a common measurement on sensor armature and some 25mm style sensors. The OP is the distance from the internal flange of a G1-¼ connection to the outer edge of the o-ring used to seal armature into a 25mm style socket.

OD - Optical Density, or Absorbance. This type of measurement is based on a logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls). For samples which scatter light, absorbance may be defined as: the negative logarithm of one minus absorbance, as measured on a uniform sample. Generally OD is used to quantify light which is ‘lost’ to a detector system through other mechanisms.

OPC - OPC is the interoperability standard for the secure and reliable exchange of data in the industrial automation space and in other industries. It is platform independent and ensures the seamless flow of information among devices from multiple vendors. The OPC Foundation is responsible for the development and maintenance of this standard.

OQ - Operational Qualification. Verification that the equipment supplied performs to manufacturer’s specifications. OQ may involve specification review, calibration, and measurement within the process.

ORP - Oxidation Reduction Potential: The measurement of the spontaneity of a chemical species to gain or lose electrons to an electrode and thereby be reduced or oxidized respectively. Each species has its own intrinsic redox potential. In general the more positive the reduction potential the greater the species affinity for electrons and tendency to be reduced. ORP can reflect the antimicrobial potential of water, among other things.

OTR - Oxygen Transfer Rate. The rate at which gas phase oxygen is dissolved into the liquid media. PID control based off the dissolved oxygen measurement is used to control the OTR. Most bioprocesses try to control at 30 to 60% air saturation to ensure proper OTR.

OUR - Oxygen Uptake Rate. This value is based on how quickly cells use the dissolved oxygen present in the liquid media. Cell type and growth phase will impact OUR.


PAT - Process Analytical Technology. The systematic analysis and control of a manufacturing process throughout all stages to ensure the quality of the final product. The PAT concept was defined by the US FDA to measure critical process parameters (CPP) in-line or on-line which affect critical quality attributes (CQA) of the product.

PCS - Process Control System - General term for the sensor/controller/transmitter/logic systems or general programmable electrical and mechanical equipment used to measure, monitor. And control a process. (such as SCADA/PLC/DCS)

PEEK - Polyether ether ketone: a colourless organic thermoplastic polymer. PEEK is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained to high temperatures. Due to its excellent machinability PEEK is used for many sensor components. For example, the sensor shaft of the Conducell 4UxF conductivity sensors is made from PEEK.

PG13.5 - This is a standard for the male threaded connection used on 12mm style sensors. “PG” is an abbreviation for the German term Panzer-Gewinde. The thread pitch is slightly different than conventional Metric or NPT style threads. Female PG13.5 connections are commonly found in the headplates of laboratory style glass bioreactors.

pH - potential of hydrogen ions. A logarithmic scale of the concentration of hydrogen ions in a aqueous solution. Used to indicate the presence of acids or bases in the solution.

PHI - PHI glass is a proprietary glass used in pH sensors, promoted as the longest lived pH glass in frequent SIP and autoclavation with low drift, small shift after cleaning, and general chemical robustness. Recommended for bioreactor installations found in R&D, upstream and downstream pharmaceutical applications.

PID - PID is an acronym for "Proportional / Integral / Derivative". This is a method of feedback control to optimize holding a process to a setpoint. PID control is frequently used in bioprocesses for controlling variables such as temperature and dissolved oxygen.

PLC - Programmable logic controller. An industrial computer adapted for the control of manufacturing processes (assembly lines, machines, robotic devices, or any activity that requires high reliability, ease of programming, and process fault diagnosis.

pO2 - Partial pressure of oxygen. Polarographic and Optical dissolved oxygen sensors measure based on the partial pressure of oxygen exerted against the sensing element.

PP - Partial Pressure. Different molecules, also known as molecular species, will add different amounts of pressure to a given sample volume. Gas molecules collide with one another in any given space to produce the phenomena of pressure, the pressure created from all molecules in a mix of molecules is the total pressure, whereas the pressure created from one of the species would be the partial pressure with respect to that species.

PPB - Part per billion. This unit can be measured as a per volume, per mass, or per molecule basis. For dissolved gas measurement applications mass is commonly used thus PPB = microgram/Liter.

PPM - Part per million. This unit can be measured as a per volume, per mass, or per molecule basis. For dissolved gas measurement applications mass is commonly used thus PPM = milligram/Liter.

PQ -Performance Qualification. Generally the final test of the IQ / OQ / PQ process. Performance Qualification is an actual test of the product under normal production conditions to ensure that the product performs to specifications.


QBD - Quality by Design. A method of design principles used to optimize a product through removing failures and creating features in response to understanding customer needs.


RQ - Respiratory Quotient. The volumetric ratio of CO2 released over the volume of oxygen absorbed. This value may be used to estimate metabolic activity.

RTD - Resistance Temperature Detector. Sensors used to measure temperature through. Typically made of platinum, nickel, or copper. The material has an accurate resistance-temperature ratio which is used to provide an indication of temperature. 100 ohm (Pt100) or 1000 ohm (Pt1000) elements are commonly used in Hamilton sensors.

RS485 - A standard defining the electrical characteristics of drivers and receivers for use in serial communications systems. The standard is jointly published by the Telecommunications industry Association and Electronic industries Alliance (TIA/EIA). Communications networks implementing the standard can be used effectively over long distances and in electrically noisy environments. Due to its multiple receiver friendly linear multidrop bus, this standard is useful in industrial control systems and similar applications. Modbus communication protocol used in Hamilton Arc sensors is a good example of RS485 serial communication.

RX - Short for "redox" which may be a shorten term for a reduction reaction or another term for ORP (oxidation reduction potential) in general.


S7 - A common style of threaded electrical connector used on laboratory pH sensors. S7 and S8 connectors are identical however S7 connectors have no external mounting thread.

S8 - A common style of electrical connector used on process pH sensors. S8 connectors have two contact points thus carry the mV signal of a pH sensor. They may have external PG13.5 male threads for mounting into process connections such as those found on a bioreactor headplate or a Hamilton housing.

SCADA - Supervisory Control And Data Acquisition. Software that is used to control and capture data from a process. SCADA software may be used to monitor a single process such a bioreactor OR may be used on a computer connected to multiple processes through digital protocol such as Ethernet.

SCAR - Supplier Corrective Action Report. A document that identifies possible issues or defects found in a product. The SCAR provides background details regarding the non-conforming product, root cause analysis, and information on corrective actions to prevent recurrence.

SIP - Steam or Sterilize In Place. A common method of sterilizing the insides of stainless steel bioreactor vessels and related piping. Steam is injected into the vessel and the temperature is held at 120 to 140C for at least 30 minutes to kill any bacteria or other possible contaminants. SIP is always done prior to a new batch to ensure sterility.

SOP - Standard Operating Procedure. A detailed list of instructions to carry out a task. For example, a technician may have an SOP for calibration of a sensor. Following the SOP ensures that the task is performed the same way every time.

SUB - Single Use Bioreactor


T82 - A type of 4-pin twist lock style sensor electrical connector commonly used on polarographic dissolved oxygen sensors. The design is similar to circular mil spec connectors. Sometimes referred to as a D4 connector.

TCD - Total Cell Density. A measurement representative of the volume of living and dead cells in a solution.

TPO - Total Package Oxygen. This term is used in brewing and winery production. TPO accounts for all sources of oxygen within the bottle or can. These sources include dissolved oxygen within the liquid, oxygen in the headspace of the container, and any oxygen permeation from the sealing mechanism (ie - cork or screw-top).


UPW - Ultra Pure Water. This is an acronym used in many industries to refer to highly purified water that has all contaminants removed. Contaminants would include any organic compounds, dissolved gases, bacteria, and any other ions. The level of purity is typically measured using a two-pole conductivity / resistivity measurement. Ultra pure water will have a minimum conductivity of 0.055 µS/cm (resistivity of 18.18 Mohm/cm) at 25°C. Rising conductivity will indicate the presence of contaminants.

USP - U.S. Pharmacopeia. USP is a non-profit regulatory agency involved in qualifying standards for medicines, food, and dietary supplements. Common examples of USP regulations as applied to measurement equipment include USP Class VI testing for the biocompatibility of plastics and elastomer materials and the categorization of water purity for pharmaceutical and analytical purposes.


V - V Glass. This is a specialty pH membrane glass type designed for low temperature applications.

VCD - Viable Cell Density. A measurement representative of the volume of living cells in a solution.

VP - A common acronym for Variopin electrical connectors used on sensors. VP connectors are rated for IP68 and autoclavation. The design can be easily wiped down to prevent moisture from interfering with the measurement signal. VP connectors may have from 2 to 11 contact pins to provide power and transmit a measurement signal.


WFI - Water For Injection. WFI water is purified water suitable for manufacturing of pharmaceuticals that will be delivered through human injection. Guidelines for WFI water are set by the U.S. and European Pharmacopoeia. Purity is normally verified by raw conductivity measurements.