HTS Eclipse – Adjustable Orifice Valves ALO / ALO-R Series

Overview

The Honeywell Eclipse ALO and ALO-R Series are adjustable limiting orifice valves designed for installation in gas supply lines feeding nozzle mix burners. Their primary function is precise gas flow adjustment to achieve and maintain the desired air/gas ratio. The unique V-port design enables extremely fine ratio adjustment, making these valves well suited for demanding combustion tuning applications.

The ALO Series is available in five pipe sizes from 3/4″ to 2″, with natural gas capacities from 213 cfh to 16,469 cfh depending on valve size and pressure drop. The ALO-R is a right-angle version offering the same adjustability in applications where a 90° flow path is required. Maximum inlet pressure for both series is 40 psi.

Features & Benefits

• V-port stem design allows extremely fine air/gas ratio adjustment for accurate combustion tuning
• Five pipe sizes (3/4″ to 2″) accommodate a wide range of burner capacities
• Simple field adjustment — remove cap, turn stem clockwise to reduce flow or counterclockwise to increase flow
• Protective cap prevents post-adjustment tampering and protects packing nut threads
• ALO-R right-angle variant available for installations requiring a 90° flow path
• Maximum inlet pressure of 40 psi supports a broad range of gas supply conditions

Technical Specifications

• Pipe sizes: 3/4″ (ALO-3), 1″ (ALO-4), 1-1/4″ (ALO-5), 1-1/2″ (ALO-6), 2″ (ALO-8)
• Flow coefficient (Cv) full open: 4.70 (ALO-3) to 24.81 (ALO-8)
• Natural gas capacity range: 213 cfh to 16,469 cfh (0.60 SG gas, varies by size and pressure drop)
• Maximum inlet pressure: 40 psi
• Minimum application temperature: -20°F (-28°C) — consult factory for applications below this limit
• Body material: Globe valve body
• Bonnet and cap: Brass
• Function: Limiting orifice — not a substitute for a shutoff valve; a manual shutoff valve must precede installation

Applications

• Gas flow adjustment in nozzle mix burner supply lines
• Air/gas ratio control for industrial and commercial combustion systems
• Flow limiting in burner train assemblies where precise ratio setting is required
• Process heaters, furnaces, and boiler burner trains
• Any application requiring repeatable, field-adjustable gas flow restriction up to 40 psi

Models / Configurations

• ALO-3 – 3/4″ pipe size, Cv 4.70 full open; straight-body globe valve configuration
• ALO-4 – 1″ pipe size, Cv 6.54 full open; straight-body globe valve configuration
• ALO-5 – 1-1/4″ pipe size, Cv 12.24 full open; straight-body globe valve configuration
• ALO-6 – 1-1/2″ pipe size, Cv 13.79 full open; straight-body globe valve configuration
• ALO-8 – 2″ pipe size, Cv 24.81 full open; straight-body globe valve configuration
• ALO-R Series – Right-angle body version of the ALO; available in corresponding sizes for 90° flow path installations

Adjustable Orifice Valve Accessories

• Adjustable Orifice Gas Cocks (Lever Handle) – 1/2″ NPT or RP female, brass, Cv 2.9, rated to 1 psig; used for small-capacity gas adjustment applications at low pressure
• Adjustable Orifice Gas Cocks (Butterfly Handle) – 1/4″ NPT female x male, brass, Cv 0.3, rated to 1/2 psig; compact gas cock for very low-flow adjustment
• Manual Shutoff Valve (Lubricated Plug Cock) – Required upstream of all ALO and ALO-R installations per manufacturer guidelines

Documentation