Flame King 2-Stage Automatic Changeover Propane Regulator ACR-2a — Dual-Cylinder RV Regulator, 11" WC Output

Flame King ACR-2a is a two-stage automatic changeover propane regulator that keeps gas flowing from a backup cylinder while you remove or refill the empty tank.

This compact, UL-listed regulator is built for RVs, vans, and trailers with dual-cylinder setups. It automatically switches from the primary cylinder to the reserve when pressure drops, maintains steady downstream pressure under varying demand, and is factory-set for 11" WC output with a lockout near 14.9" WC. Designed for reliability and user convenience, the unit accepts 1/4" SAE inverted flare inlets and delivers through a 3/8" NPT female outlet. The ACR-2a ships without pigtails so you can pair it with Flame King’s approved hoses and pigtails to match your RV installation.

How does this regulator keep propane flowing during a tank change?

The ACR-2a monitors upstream pressure and automatically moves supply to the reserve cylinder when the primary is depleted. This means you can remove and refill the empty bottle without interrupting appliances. It includes a lockout to prevent draw from an over-pressurized or faulty cylinder.

• Automatic switching between primary and reserve tanks
• Allows cylinder removal without shutting off appliances
• Built-in lockout pressure to block unsafe sources
• Works with standard dual-tank RV layouts

What are the performance specs and connections I need to know?

The regulator is rated for up to 345,200 BTU and uses a two-stage design to maintain stable downstream pressure. Inlets are 1/4" SAE inverted flare and the outlet is 3/8" NPT female pipe thread, giving compatibility with common RV fittings when paired with proper pigtails or hoses.

• Factory set to 11" WC output; lockout near 14.9" WC
• Rated capacity: 345,200 BTU
• Inlets: 1/4" SAE inverted flare; outlet: 3/8" NPT female
• Two-stage design for steady pressure under changing loads

Which hoses and pigtails should I use with the ACR-2a?

This regulator is shipped without pigtails so you can select the correct lengths and fittings for your installation. Flame King recommends specific inverted-flare pigtails and a 48" thermoplastic hose to match common RV layouts while avoiding NPT pigtails.

• Compatible with Flame King 48" Thermo Plastic Hose (Model 100383-48)
• Works with 12–18" inverted-flare pigtails (Models E12INPT, E15INPT, E18INPT)
• Avoid using NPT pigtails as they are not recommended for this connection
• Select pigtail length to prevent stress on fittings and simplify tank swaps

What safety and installation details should I consider?

Flame King assembles critical adapter connections with high-strength thread locker to secure fittings and reduce leak risk. Always follow local codes and RV manufacturer guidance when installing regulators, and use qualified technicians if you’re unsure.

• Critical connections use thread-locker (Loctite) to resist loosening
• UL listed design and rated capacity for RV systems
• Install in a well-ventilated area away from ignition sources
• Follow local codes and use approved hoses and connectors

Who is this for: The Flame King ACR-2a is ideal for RV, van, and trailer owners who run dual propane cylinders and want uninterrupted gas service during tank swaps. It suits DIY installers familiar with RV propane systems and professional installers looking for a reliable, UL-listed automatic changeover regulator. If you need continuous appliance operation, steady pressure under varying loads, and compatibility with standard inverted-flare fittings, this regulator is engineered to fit those requirements.