How to choose a proportioner

Start with output, not price. Rate a machine by pounds per minute at the pressure you actually spray, then match it to how many guns run at once. One gun on a large machine is fine; two guns on a small one starves both.

Check the electrical service before anything else. Primary heaters and hose heat draw hard, and an undersized supply shows up as ratio drift and soft foam rather than a tripped breaker. Then confirm your hose length is within the machine’s heated capacity — every added section costs you temperature at the gun.