FLOMIXER - Venturi mixers

Description

Flomixers are proportional Venturi‑type air‑gas mixers designed to supply burners with stable, balanced combustion mixtures over a wide modulation range. Made from compact aluminum components, they operate by using the kinetic energy of an incoming air stream to suction gas and deliver a homogeneous mixture. Air enters through an air sleeve and accelerates through a jet, creating a strong suction zone of approximately –5 mbar. This negative pressure draws gas from a zero‑pressure chamber, through an adjustable gas valve, into the mixing throat. The air‑gas mixture then passes through a pressure conversion chamber before being discharged toward burner manifolds.

Flomixer performance depends on a stable relationship among three pressures—air (P1), gas suction (P2), and mixture (P3)—as well as three flow sections representing air, gas, and mixture cross‑sections. If these remain balanced, the air‑gas proportion stays constant even when operating conditions vary. Proper sizing of mixture piping is essential: downstream pressure losses must remain below 2.5 mbar to prevent P3 from rising and disrupting Venturi suction.

Flomixers can achieve 75–100% aeration and adapt to any burner type when matched correctly. Burner selection methods include: (1) capacity basis at full aeration, (2) reduced‑aeration capacity basis, (3) burner area basis corrected by discharge coefficients, and (4) low mixture‑pressure correction for ribbon or multi‑port burners. Tables in the bulletin define selection capacities, multipliers, and usable insert sizes.

Four possible assembly configurations combine mixer bodies with air sleeves, butterfly valves, and gas adjusters. Codes reflect inlet and outlet diameters and insert machining. Flomixers are installation‑flexible, allowing right‑/left‑hand and vertical/horizontal mounting. Accessories such as zero regulators can be added when multiple mixers share one gas supply, provided gas pressure remains at true zero.

Maintenance is straightforward: the entrainment insert is easily accessible for inspection or cleaning without disconnecting lines. Regular checks include air‑gas pressure balance, insert condition, and piping restrictions to ensure consistent performance and correct Venturi suction behavior.