Two specialty connection families, each governed by a code, not a preference. Instrumentation double-ferrule for high-purity sample and analyzer lines on a B31.3 basis; DOT air-brake for commercial-vehicle brake circuits under 49 CFR. Neither is interchangeable with a push-to-connect fitting — the regulatory category is the answer, and there are no substitutions.
Tap any type to jump to its page. The Decision Guide further down asks three questions that funnel the spec to one of these.
Instrumentation double-ferrule SS and DOT air-brake — outside the push-to-connect family, with their own mechanism and code basis.
Analyzer / sample line → double-ferrule SS on the B31.3 basis. Commercial vehicle → DOT air-brake. The regulatory category is the answer.
The wrong fitting in a brake circuit fails roadside inspection and carries unbounded liability if a crash results. No substitutions.
Different mechanism, different installation, different code basis — an industrial machine-pneumatic fitting is never a legal substitute here.
SPC cross-lists DK-LOK on the instrumentation double-ferrule side and Alkon on the DOT air-brake side — one brand deep, code-driven specs.
Distributor-facing reading. The trade-off column is the one that closes the loop — every type buys something and gives something up. Knowing what each type costs you is how the right one gets on the quote without a callback.
Reading the brand bench column — the bar shows how many of SPC's tier slots carry an option at that product type. Both specialty families run a single brand deep because the specs are narrow and code-driven: DK-LOK on the instrumentation double-ferrule side, Alkon on the DOT air-brake side. These are regulatory categories, not push-to-connect tiers — the code sets the spec, and there is no industrial substitute.
Draw a line from the customer's answer at the top to the type name at the bottom. This is the page distributors screenshot and send to a customer the day before a quote call — so the customer comes prepared with the answers, and the call is about the brand and the budget, not the basics.
If the customer answers most of these at the first call, the second call is the quote. If they can't answer any, the specialty fittings are rarely the only spec gap — flag it and push for a site walk.
Distribution is the layer that turns a treated, regulated air supply into air at the actuator — and the layer that's invisible when it works and catastrophic when it doesn't. Every leak, every pressure drop, every blown hose, every machine-down call traced back to "the air just stopped" ultimately lives in this layer. A pneumatic system is a thousand-plus connections — header to drop leg, drop leg to FRL, FRL to manifold, manifold to valve, valve to cylinder, plus every hand-tool coupler in between — and each one is a candidate failure point. Industry audits consistently put facility-wide leak rates at 20-30% of compressor output, with the majority of those losses at fittings and joints, not at the equipment. Distribution is also where material spec meets regulatory and audit exposure — food contact, NSF certification, ATEX classification, DOT/FMCSA brake circuits, B31.3 instrumentation. Spec it right at the connection level and the rest of the system can deliver what it was designed to deliver; spec it wrong and the customer is patching leaks for the life of the plant.
Instrumentation double-ferrule for high-purity sample and analyzer lines, and DOT air-brake for commercial-vehicle brake circuits. Regulatory connection families, not push-to-connect.
The standard PTC tiers — composite, technopolymer, brass, stainless, NSF food-grade. The Sang-A flagship core of the Distribution layer.
→Push-to-connect bodies that also perform a function — rotary joints and stop fittings. The Sang-A functional-fitting line.
→The line itself — PE, PU, nylon, and FEP/PTFE matched to chemistry, pressure, and motion.
→Tool changeover at the hose end — industrial, safety, and plug halves.
→The plant header — extruded aluminum mains replacing legacy black iron.
→Downstream in Control & Valving — where an instrument or brake-circuit connection hands off to the valving that controls it.
→Tell us the end-use, the rough flow, and what climate the unit would sit in. We'll come back with a configured quote — the right type, the right tier, and the upstream gear the warranty assumes.
—. We reply within one business day with pricing, lead-time, and configured parts.