Bridges a propane pigtail or hose with a 1/4" male inverted flare end to a regulator, manifold, or T-fitting with a 3/8" female NPT inlet. Solid brass construction.
Propane systems across different RV brands and appliances don't always use the same fitting sizes — and when a pigtail hose with a 1/4" male inverted flare end meets a regulator or manifold with a 3/8" female NPT inlet, you need a small brass adapter to bridge the gap cleanly. The MB Sturgis 402142PKG is exactly that adapter: a short, solid brass fitting with a 1/4" female inverted flare on one end and a 3/8" male NPT on the other.
The female inverted flare end accepts the 1/4" male inverted flare fitting found on most MB Sturgis pigtail hoses — including the 100575 and 100833 series — without requiring thread sealant, since inverted flare connections seal on the flare seat rather than the threads. The 3/8" male NPT end threads into any compatible 3/8" female NPT port on a regulator, manifold block, T-fitting, or other downstream component, using standard right-hand thread with gas-rated pipe sealant or tape applied to the male NPT threads. Machined from brass for reliable sealing and long-term durability in propane gas service.
Accepts a 1/4" male inverted flare pigtail hose end — the fitting type used on most MB Sturgis Type 1 and POL pigtail series
Threads into any 3/8" female NPT inlet on a regulator, manifold block, T-fitting, or other downstream component
Precision machined brass body for reliable sealing, corrosion resistance, and long-term durability in propane gas service
Manufactured by MB Sturgis to the quality standards that have made them an OEM supplier since 1959
Before ordering, confirm the following: 1. Pigtail or hose end: This adapter has a 1/4" female inverted flare — it accepts a 1/4" male inverted flare fitting on your pigtail or hose. Confirm your pigtail's regulator-side fitting is a 1/4" male inverted flare. 2. Regulator or manifold inlet: This adapter has a 3/8" male NPT on the other end — it threads into a 3/8" female NPT port. Confirm your regulator, manifold, or T-fitting inlet is 3/8" female NPT. 3. If your regulator has a 1/4" female NPT inlet instead: See the MB Sturgis 402258-MBS, which has the same 1/4" female inverted flare on one end but a smaller 1/4" male NPT on the other — the correct fit for regulators with a 1/4" NPT inlet. 4. Thread sealant: Apply gas-rated pipe sealant or PTFE tape to the 3/8" male NPT threads before installation. No sealant is needed on the female inverted flare end — it seals on the flare seat.
Pigtail to 3/8" NPT Regulator: When your propane pigtail hose (100575 or 100833 series) has a 1/4" male inverted flare end and your two-stage regulator has a 3/8" female NPT inlet, this adapter bridges them without needing an intermediate hose or fitting chain. Pigtail to 3/8" NPT Manifold Block or T-Fitting: Some RV propane distribution manifolds or T-fittings use 3/8" female NPT ports. This adapter lets you connect a standard Type 1 or POL pigtail into those ports. System Modifications and Custom Hose Runs: When building or modifying an RV propane system and needing to transition from an inverted flare connection to an NPT-threaded component at the 3/8" size. If your regulator inlet is 1/4" female NPT (smaller), use MB Sturgis 402258-MBS instead.
Installation Steps: 1. Shut Off Gas Supply: Close the propane supply completely before making any fitting changes 2. Apply Thread Sealant to NPT End: Wrap the 3/8" male NPT threads with gas-rated PTFE tape or apply gas-rated pipe thread sealant — do NOT apply sealant to the female inverted flare end 3. Thread NPT End into Component: Thread the 3/8" male NPT end into your regulator's, manifold's, or T-fitting's 3/8" female NPT inlet and tighten securely 4. Connect Pigtail to Flare End: Thread your pigtail's 1/4" male inverted flare fitting into the adapter's female flare end and tighten with a wrench — hand-tight plus a quarter to half turn with a wrench is typical for flare connections 5. Leak Test: Restore gas supply and perform a soap-and-water leak test on both connections before placing the system into service Gas fitting work should be performed or verified by a qualified technician. Always leak-test before use.
In The Package: • (1) 402142PKG Brass Propane Adapter Fitting • 1/4" Female Inverted Flare (One End) • 3/8" Male NPT (Other End) NOT Included: • Gas-rated pipe sealant or PTFE tape (required for NPT end) • Pigtail hose or regulator
MB Sturgis Technical Support: Phone: (314) 291-6665 Email: [email protected] MB Sturgis Inc. has supplied OEMs, distributors, gas installers, and end users with safe LP and natural gas connection products since 1959.