Make Pneumatic Connections Air Tight

May 15, 2015
Today’s pneumatic fittings are designed to attach quickly, operate leak-free, and work for years.
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Pneumatic connectors may be underappreciated in the world of air-circuit design, but they’re nonetheless indispensable for efficient and leak-free performance. Here’s a look at some innovative connectors that offer attributes such as durability, corrosion resistance, high flow capacity, light weight, low cost, and ease-of-assembly.

Stainless Steel Pneumatic Fittings

The NITRA line of pneumatic products now includes 316 stainless-steel fittings that stand up to harsh chemicals and washdowns, and can withstand pressures up to 290 psi and temperatures to 390°. The push-to-connect male fittings, in NPT inch and BSPT sizes, feature 303 stainless-steel gripping collets with internal Viton O-ring. The fittings can be used with polyurethane, nylon, and PTFE tubing in sizes from 5/32 to 1/2 in. and 4 to 10 mm. Available fittings include straight unions, straight reducers, and male straight and bulkhead fittings. Other pneumatic connectors in the NITRA line include push-to-connect thermoplastic fittings, threaded brass fittings, quick-disconnect air couplings, and swivel air fittings.AutomationDirect, (800) 633-0405,

Pneumatic Push-in Fittings

Series QR1 fittings have a lightweight, polymer design suitable for all of the company’s pneumatic products, such as valves and cylinders. The push-to-connect-style fittings have an oval release ring with an enlarged surface area for quick, easy release of pneumatic tubing. Other features include standard nickel-plated brass threads, inch or metric (ISO G) versions, Teflon thread sealant standard on NPT versions, and a stainless-steel internal locking ring. The comprehensive line of QR1 fittings consist of the Mini design for plastic tubing ODs of 1/8 to 1/4 in. and 3 to 6 mm; and the Standard design for tubing ODs of 5/32 to 1/2 in. and 4 to 16 mm. Styles include straights, elbows, tees, Ys, Xs, manifolds, bulkheads, plugs, reducers, unions, and caps. Products such as check, ball, and flow-control valves are also included in the range of function fittings.Aventics, (859) 254-8031,

Fittings with Protective Coating

Brennan Black rust-resistant coating for tube fittings and adapters reportedly provides excellent protection in highly corrosive applications. It’s designed to protect equipment and ensure longevity in harsh environments, thus reducing downtime and replacement costs. While the industry norm for corrosion protection of fittings is 72 hr, and the company's standard CR3-plated products provide more than 110 hr of corrosion protection, Brennan Black coating applied over plating provides more than 1,700 hr of corrosion protection. It’s made of a proprietary blend of fluoropolymers, engineered plastics, and selective corrosion inhibitors, and the coating is available for all the company’s steel fittings and adapters. In addition to excellent corrosion resistance, other features include high resistance to wear, abrasion, and chipping. Working temperature range is –420 to 500° F.Brennan Industries, (888) 331-1523,

Transportation-grade Fittings

Transportation-grade fittings are high-quality, industrial push-in fittings. The line includes inch series D6000 fittings and extreme-duty (–50°C) metric series 9000 C-Truck fittings. Both series are specifically designed for maximum reliability in pneumatic systems on industrial and commercial vehicles in the harshest environments. Applications include a wide range of mobile vehicles, including on-road trucks, trailers, and buses; off-road agriculture, earth-moving, and military equipment; and railway vehicles. Fractional-sized fittings conform to DOT 571.106 and SAE J2494 performance standards, and come in 5/32- to ½-in. tube diameters.  Metric-sized fittings conform to DIN 74324:1996, DIN EN ISO 9227:2006, and DIN EN 60068-2-6:1996. and are available in 4-  to 18-mm tube diameters.Camozzi Pneumatics, (972)-998-9440,

Rugged Metal Fittings

The PN Series is a line of compact, push-in, full-metal fittings suited for heavy-duty pneumatic applications. A stainless-steel gripper and O-ring inside the fitting ensure secure and reliable tubing connections. To connect, users simply push the tubing into the fitting until it bottoms; the stainless-steel teeth grip the tubing and hold it captive. Compatible tubing types include polyamide, polyethylene, and polyurethane. Working temperature is from –4 to 160° F. Working pressure depends on the tubing, but doesn’t exceed 260 psi. Vacuum rating is to 28-in. Hg. The fittings come in a range of styles, including male and female straights, elbows, swivel elbows, tees and swivel tees, reducers, unions, and Y fittings. Sizes vary by style. For example, the PN 11 taper straight male includes 16 variations for tube sizes from ⅛ to ½ in. OD. The fittings are delivered read-to-use with PTFE pre-applied to all threads. They can be disassembled and reconnected several times without the durable PTFE coating peeling off.

C.Matic, +39 0362 805246,

Quick-connect Fittings

The Minimatic J-Series quick connects consist of two component parts that are joined to form the complete connector. The valve body contains a two-way, spring-loaded poppet valve that’s typically connected to the main air supply. When the poppet isn’t depressed, this valve shuts off the air supply. The cap contains a valve depressor that, when assembled to the valve body, depresses the poppet. This permits airflow from the main supply to the pneumatic circuit or downstream equipment. The line includes many styles and connectors with flows rated at 14 scfm @ 100 psig.Clippard Instrument Laboratory, (513) 521-4261,

Clean-design Fitting

The NPCK clean-design fittings are suited for use in food-handling and splash zones in the food industry, as well as for process-automation and the pharmaceutical-industry applications. Targeted for use in cleaning-intensive areas, the NPCK fulfills all Clean Design requirements and is FDA-compliant. The NPCK’s connector and nut are made of high-grade stainless steel, and the sealing ring is PEEK. This lets the connector handle a wide range of cleaning agents and resist corrosion and high temperatures. In addition, the special union-nut design prevents dirty edges and the build-up of microorganisms or other contamination. Operating pressures range from –0.95 to 12 bar, and operating temperatures range from –20 to 120°C. Sizes include M5, G⅛, G¼, and G⅜.Festo Corp., (631) 435-0800,

Leak-free Plug

Pressurized air is clean and suited for a wide range of industrial tasks, but it can be expensive. Even the smallest system leak is costly. To help solve that problem, the HN P screw plug was designed for systems that must be leakproof. The compact design includes a steel body coated for corrosion resistance, with an integrated O-ring that provides tight sealing. Pressure rating is to 232 psi. The plug’s dimensions meet ISO 16030, and the NBR Shore 70 O-ring is rated for temperatures from –4 to 248° F. Other body and seal materials are available on request. Thread sizes range from M3 to M7 and G1/8 to G1 (Class A). The low-cost HN P plugs provide reliable sealing, and are well-suited for limited-space installations.Heinrichs USA, (859) 371-4999,

Pneumatic Test Connectors

The FE and FI Series of automated quick connections are designed for volume production testing with uniform seal movement.  The connectors cover a full range of English and metric male and female ports, as well as NPT/BSPP/BSPT threads.  New offerings include standard 1- and 2-in. shaft extensions for remote or offset ports. Among the sealing material options are neoprene for low-abrasion testing, urethane for high pressure and lubricant resistance, and FDA-approved materials for medical-device testing.FasTest, (800) 444-2373,

Panel-mount Adapter Plate

With the 501 Series panel-mount adapter plate, OEMs and end users can connect the company’s compatible pneumatic valve manifold directly to a panel in the wall or floor of a cabinet. The adapter plate saves space and simplifies panel layout and construction by eliminating the need for complex tubing routing and bulkhead fittings, as well as reducing custom machining and drilling. The design minimizes leaks; cuts assembly costs and cabinet size; and simplifies maintenance and troubleshooting. The 501 Series has a unique shut-off configuration that permits easy isolation (hot swapping) and replacement of valves without disrupting operations. It comes in three sizes — for 8, 12, and 16 valves — and is available in stainless steel and anodized aluminum. The panel-mount adapter plate suits applications that install directional control valves in a cabinet due to environmental or space constraints. Applications include food and beverage, pharmaceutical, and packaging machinery, plus general machine automation.Numatics, (888) 686-2842, www.numatics.comBrass Fittings

Brass push-to-connect fittings, which offer quick assembly and full-flow design, will find use in polyethylene, nylon, and polyurethane tubing. Styles include bulkhead unions, tube-to-pipe connectors, 90° elbows, and tees in a variety of versions. Depending on the part, sizes can range from ⅛- to ½-in. tube and 1/16- to ½-in. pipe. Pressure ratings range from 250 to 350 psi.
Fairview Fittings, (800) 688-4088,

Push-to-connect Pneumatic Fittings

PTC push-to-connect fittings provide quick and simple tubing connection and disconnection. All components, including the release collar, are stainless steel, suiting them for use in corrosive environments and applications requiring “clean” materials. A captured O-ring face seal ensures leak-tight operation. Buna-N O-ring seals are standard; fluorocarbon, silicone, and EPDM are optional. Configurations include 10-32 threaded straights, adjustable-position elbows and tees, as well as “tube to tube” straight unions, elbows, and tees for ¼- and ⅛-in.-OD tubing. The fittings can be used with a variety of tubing materials, such as polyurethane, polyethylene, and copper. For corrosion resistance and high temperatures, the ¼-in.-OD PTC fittings also work with stainless-steel tubing.Beswick Engineering, (603) 433-1188,
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About the Author

Leah Scully | Associate Content Producer

Leah Scully is a graduate of The College of New Jersey. She has a BS degree in Biomedical Engineering with a mechanical specialization.  Leah is responsible for Hydraulics & Pneumatics’ news items and product galleries. 

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