AR20399 | Gymatic 3/B Unloader Valve Injector 3650 PSI Adjustable

AR20399 Gymatic 3/B Unloader | 3650 PSI, Up to 5.5 GPM, Adjustable Chemical Injector

The AR20399 is the Annovi Reverberi Gymatic 3/B unloader for RK, RR and XM series pumps, rated to 3,650 PSI at up to 5.5 GPM. It bolts straight onto the pump and controls pressure: when the trigger closes, it sends flow to its built-in bypass so the pump is not dead-headed. No external bypass hose is needed.

Its built-in chemical injector is adjustable, so you can set how much detergent it draws: light for rinsing, heavier for degreasing.

What It Fits

• Pumps: Annovi Reverberi RK, RR and XM series.
• Flow: up to 5.5 GPM.
• Pressure: up to 3,650 PSI.
• Connections: 1/2 in. male NPT inlet, 3/8 in. male NPT outlet.

Not sure it fits? Text a specialist at (505) 226-6061 with your pump model and a photo of the old unloader and we’ll confirm.

How to Use the Injector

• The injector draws detergent only at low pressure. Switch to a low-pressure soap nozzle to pull chemical.
• Turn the injector adjuster to set the detergent ratio for the job.
• Flush it with clean water after each chemical job to prevent residue and blockages.

Good to Know

• This is a trapped-pressure unloader: when you release the trigger, pump pressure drops to zero but the hose stays pressurized.
• Set the working pressure with a gauge, and keep a thermal relief valve on the pump to protect it during long bypass periods.
• Prefer a fixed injector? The AR20081 and AR20082 are the same Gymatic 3/B with fixed injectors. No injector needed? See the AR20242.

AR20399 Specifications

• Model: AR20399 (Gymatic 3/B)
• Max Pressure: 3,650 PSI
• Max Flow: 5.5 GPM
• Inlet: 1/2 in. male NPT
• Outlet: 3/8 in. male NPT
• Injector: Adjustable
• Bypass: Built in
• Body: Brass
• Max Water Temperature: 140°F
• Fits: AR RK, RR and XM series pumps
• Brand: Annovi Reverberi

Shipping: Usually ships via UPS in 1 to 3 days.