Regulator Sizing Tools / Model 121 / 122
Model 121 / 122 Sizing ToolBeta
Combustion regulators for commercial and industrial burners, with a precision-machined knife-edge orifice and a soft-seat valve. The 121 is available pilot-operated, pressure-loaded and with V-port options; the 122 uses internal sensing as standard.
What you'll need
- Inlet pressure — psi or bar
- Outlet pressure / set point — psi, in. w.c. or bar
- Max gas load or flow rate — CFH, CMH or BTUH
Optional, improves the result
- Minimum flow rate
- MAOP (maximum inlet pressure)
- Desired pipe size
- Over-pressure protection — sized as a monitor
- Generator or high-efficiency boiler load percentage
- Gas type — natural gas, propane, or another gas by specific gravity
- Altitude above 3,000 ft
Operating envelope
| Input | Accepted range |
|---|---|
| Inlet pressure | 8" w.c. – 60 psi |
| Outlet pressure | 1.5" w.c. – 10 psi |
| Outlet vs. inlet | must be lower |
| MAOP | ≥ inlet pressure |
The ranges above cover both models together. Model 122 is only offered up to a 2 psi set point, or 1 psi when a monitor is required — above that the tool returns Model 121 options. Model 121 regulators also have outlet pipe sizing requirements, and the result will state the pipe size it was sized for.
Sizing Tool
Open the Model 121 / 122 Sizing Tool
The tool opens in a new tab so you can keep this page open for reference. It returns the body, orifice, spring and calculated capacity, along with the Holland Supply part number and the full sizing tables.
Launch the Model 121 / 122 Tool ↗First visit of the day may take about 30 seconds to start up. If you see a message saying the tool is asleep, click “Yes, get this app back up!” and give it a moment.
On a phone? When the tool opens, the input fields start hidden. Tap the » arrows at the top-left of the tool to slide the input panel in, fill it in, then tap the arrows again to close it and see your result.
Not sure this is the right model? The General Sizing Tool compares every USG regulator and recommends one for your conditions.
Preliminary selection only. This tool provides a starting point based on the values entered and does not account for every variable in a field installation — including inlet pressure variation, ambient temperature, elevation, piping losses, venting requirements, over-pressure protection strategy, and applicable codes. Final regulator selection, installation and setting must be performed by qualified personnel in accordance with the product installation and maintenance manual and all applicable federal, state and local codes. Improper regulator selection or installation can result in over-pressurization, property damage, serious injury or death. Contact Holland Supply Company to review any selection before ordering.