The Caleffi 549509US 001 is a 4-in-1 combination hydraulic, air, dirt and magnetic separator with 2" union-body (supplied without tailpieces) connections, rated for 37 gpm at a maximum working pressure of 150 psi. It installs between the heat source circuit and the distribution circuits of a hydronic heating or chilled water system to provide hydraulic, air, dirt and magnetic separation.
Caleffi specifies this series for hydronic heating and chilled water systems containing a primary production circuit with its own pump and a secondary user circuit with one or more distribution pumps, where pump interaction would otherwise cause abnormal variations in circuit flow rates and pressures. Caleffi states the separator should be sized to the greater of the primary or secondary circuit flow rate; this model is rated for 37 gpm. Source: 01249/22 NA, Operating principle and Hydraulic characteristics.
Key Features
Primary/Secondary Hydraulic Decoupling
A low pressure-loss zone lets the boiler circuit and the distribution circuits operate independently, so neither pump interferes with the other. Rated for 37 gpm.
Air Separation to Micro-Bubble Level
A stainless steel or HDPE coalescing element releases entrained air down to micro-bubble size and vents it automatically, achieving 100% removal to micro-bubble level.
Dirt Separation to 5 Micron
The same internal element and the vessel's low-velocity volume capture non-ferrous particulate down to 5 µm (0.2 mil), collecting it clear of the flow stream.
Neodymium Magnetic Ferrous Capture
A rare-earth magnet assembly sited outside the flow path removes magnetite and other ferrous debris with up to 100% efficiency and no added pressure drop, delivering 2-1/2 times the ferrous removal of a standard air and dirt separator.
Wall Mounting Bracket Included
A polyester painted carbon steel support bracket ships with the separator for direct wall mounting. Pre-formed PE-X insulation is available separately for field installation.
Technical Specifications
| Product Line | SEP4 |
| Series | 5495 |
| Connection Size | 2" |
| Connection Type | Union Body, No Tailpieces |
| Connection Style | Union |
| Separation Functions | Hydraulic, air, dirt and magnetic separation (4-in-1) |
| Rated Flow | 37 gpm |
| Fluid Volume | 3.5 gal |
| Air Separation Efficiency | 100% removal to micro-bubble level |
| Particle Separation Capacity | 5 µm (0.2 mil) |
| Ferrous Impurity Separation | Up to 100% removal |
| Magnet Type | Neodymium rare-earth |
| Maximum Working Pressure | 150 psi (10 bar) |
| Working Temperature Range, Uninsulated | 32 - 230 °F (110 °C) |
| Working Temperature Range, Insulated | 32 - 210 °F (0 - 100 °C) |
| Suitable Fluids | Water and non-hazardous glycol solution to 50% |
| Body Material | Epoxy resin painted steel |
| Internal Element Material | HDPE |
| Union Nut Material | Cast iron |
| Drain Valve | 3/4" garden hose thread |
| Thermowell Tap | 1/2" female straight thread |
| Support Bracket | Polyester painted carbon steel, included |
| Insulation | Not included; field-installed PE-X jacket available separately |
| Supplied As | Separator body only, without tailpieces or union nuts |
| Product Weight | 29 lb |
Specifications on this page are taken from Caleffi North America technical brochure 01249/22 NA and the associated submittal and installation documents linked below. The US suffix is defined in 01249/22 NA page 1, which lists 54950xUS as the body supplied without tailpieces; the size digit follows the same dimension table as the 54950x union models. Last verified July 2026.
Documentation
Design Resources
Related Products
- Caleffi 549509A : SEP4 2" NPT Union
- Caleffi 549599A : SEP4 2" Sweat Union
- Caleffi 549569A : SEP4 2" Press Union
- Caleffi 549552A : SEP4 2" ANSI Flanged
- Caleffi NA10797 : Wall Mounting Bracket for 2" Union 548 and 5495 Separators
- Caleffi NA10425 : Temperature Pocket Well Kit for 548 and 5495 Union Separators
Frequently Asked Questions
What does the Caleffi 549509US 001 do in a hydronic system?
The Caleffi 549509US 001 is a 4-in-1 combination hydraulic, air, dirt and magnetic separator with 2" union-body (supplied without tailpieces) connections. It creates a low pressure-loss zone between the boiler circuit and the distribution circuits so that each pump works only against its own loop, which eliminates pump conflict without relying on closely spaced tees. It is rated for 37 gpm and holds 3.5 gallons.
How does the Caleffi 549509US 001 differ from a plain hydraulic separator?
A plain hydraulic separator performs one function. The 549509US 001 performs four in a single vessel: hydraulic separation, air separation to micro-bubble level, dirt separation to 5 microns, and magnetic capture of ferrous impurities. Caleffi rates the magnetic function at 2-1/2 times the ferrous removal performance of a standard air and dirt separator.
What flow rate is the Caleffi 549509US 001 rated for?
Caleffi rates the 2" 549509US 001 at 37 gpm with a fluid volume of 3.5 gallons. A hydraulic separator should be sized to the greater of the primary or secondary circuit design flow rate, not to the pipe size alone.
Is the Caleffi 549509US 001 ASME code stamped?
No. The 549509US 001 is rated for 150 psi maximum working pressure but is not ASME code stamped. Where a project specification calls for an ASME stamped and National Board registered vessel, use the corresponding Caleffi NA-prefix model.
Does the Caleffi 549509US 001 come with insulation?
No. Union-connection separators ship with a wall mounting bracket but without insulation. A pre-formed closed-cell PE-X jacket sized for this model is available separately for field installation.
- Type:
- Hydraulic Separator
- Separation Functions:
- Hydraulic + Air + Dirt + Magnetic
- Product Line:
- SEP4
- Series:
- 5495
- Connection Style:
- Union
- ASME Code Stamped:
- No
- CRN Registered:
- No
- Insulation Included:
- No
- Connection Type:
- Union Body No Tailpieces
- Connection Size:
- 2 inch
- Max Operating Pressure:
- 150 psi
