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Cole-Parmer Technical Library

Fittings Selection Guide

Selecting Your Fittings    Basic Fitting Types    
Pipe Thread Sizes   
Certificates of Fittings Compliance

After you've decided on the right pump, chromatography system, or fermentation equipment, you'll want to make the right connections. The wrong fittings can cause leaks, unwanted flow restrictions, and costly downtime. The proper fittings let your equipment do the work that you intend it to do. That's why Cole-Parmer offers such a large selection of fittings. Whether you're connecting microbore tubing or pipes, you'll find the right fitting for your application among the wide range of fitting types and sizes offered here.

Selecting Your Fittings
  1. Consider the Tubing Used
    Barbed fittings work best with flexible tubing such as silicone or PharMed®. Compression fittings work well with rigid tubing such as PTFE or polypropylene.
  2. Determine Material Compatibility
    Fluids that are incompatible with fitting material may cause leakage or system damage. For highly corrosive fluids, PTFE fittings are best. See our Chemical Resistance Charts (see links below) to check the material compatibility of your fluid.
  3. Check Temperature and Pressure Conditions
    Make sure the fittings you choose are rated for your operating conditions. Most fittings are not capable of performing at their maximum temperature and maximum pressure ratings simultaneously.

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Basic Fitting Types

Barbed Fittings
slide into soft tubing. Tubing elasticity holds the tubing onto the fitting for low-pressure installations.


Cam Fittings
are quick-disconnecting fittings to use with hose. Connect a female coupler to a male adapter and pull down the arms for a secure connection. Capable of withstanding high-pressure applications.


Chromatography Fittings
are a type of compression fitting designed for HPLC and other high-pressure applications. These fittings withstand pressures as high as 1000 psi.


Compression Fittings
have a nut that compresses rigid tubing against fitting body for high-pressure applications.


Luer Fittings
are designed to work with microtubing and luer-type syringes. Standard-sized connecting ends make luer fittings, stopcocks, and manifolds completely interchangeable for surefire installations.


Pipe Fittings
are threaded in NPT (National Pipe Taper), UNF (Unified Fine Thread), or BSP (British Standard Pipe) sizes for permanent, high-pressure pipe connections.


Quick Disconnect Fittings
allow you to make and break tubing connections without separating tubing from fitting. Available with barbed, pipe, compression, and John Guest® connections.


Sanitary Fittings
are designed for contamination-free tubing connections. Most of these autoclavable fittings meet FDA and USDA requirements and 3A Sanitary Standards.

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Pipe Thread Sizes

Originally, pipes were specified with a standardized outside diameter (OD) and wall thickness so that the nominal pipe size would approximately equal the inside diameter (ID). Because this relationship between the OD, wall thickness, and nominal pipe size no longer holds true, NPT (National Pipe Taper) and UNF (Unified Fine Thread) inch scales are different from the standard English inch scale.

Cole-Parmer also offers BSP British Standard Pipe) fittings for connecting systems that use both NPT and BSP thread configurations. See the table below for a comparison of these two thread styles.

Size Threads per inch
1/8" 27 28
1/4" 18 19
3/8" 18 19
1/2" 14 14
3/4" 14 14

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Certificates of Fittings Compliance Cole-Parmer now offers natural polypropylene barbed fittings that comply with FDA and USP regulations. If you need documentation to prove that your fluid-handling components conform to certain standard specifications, we will include a certificate of fittings compliance with your order at no charge—just request your certificate when you place your order.

Certificates list your company's name, PO number, order reference number, fitting catalog number, product formulation, compound number, lot number, and the regulations with which the fittings comply: FDA (United States Food and Drug Administration) Sections 117.1520 (a) 1, 117.1520 (b), 117.1520 (c) 1.1 and USP (U.S. Pharmacopoeia) XXI Class VI.

Look for the "certification ribbon" throughout this section to easily identify when a certificate of fitting compliance is available.

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Related Links: Printer-friendly page

Complete Selection of Fittings
Complete Selection of Tubing

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