The Caleffi NA548150A is a hydraulic separator with 6" ANSI B16.5 Class 150 flanged connections, rated for 484 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 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 484 gpm. Source: 01076/24 NA, Operating principle and Hydraulic characteristics. The NA-prefix vessel is ASME Section VIII stamped and National Board registered, as stated under Agency approval.
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 484 gpm.
High-Capacity Automatic Air Vent
A float-operated brass automatic air vent continuously discharges air that collects at the top of the vessel, with no manual venting routine required.
Blowdown Drain Valve
A brass drain valve at the base of the vessel purges settled impurities without taking the system offline.
ASME Section VIII Code Stamped
Designed and built to Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code, National Board registered and CRN registered, stamped for 150 psi working pressure with the ASME U stamp.
ANSI B16.5 Class 150 Flanged Ports
Raised-face flanged connections simplify installation and removal on large-diameter mains and carry the full rated flow of the vessel.
Technical Specifications
| Product Line | Hydro Separator |
| Series | NA548 |
| Connection Size | 6" |
| Connection Type | ANSI Flange |
| Connection Style | Flanged |
| Separation Functions | Hydraulic separation |
| Rated Flow | 484 gpm |
| Fluid Volume | 23.2 gal |
| Maximum Working Pressure | 150 psi (10 bar) |
| Vessel Working Temperature Range | 32 - 270 °F (0 - 132 °C) |
| Suitable Fluids | Water and non-hazardous glycol solution to 50% |
| Body Material | Epoxy resin painted steel |
| Internal Element Material | 304 stainless steel |
| Flange Standard | ANSI B16.5 Class 150 RF |
| Drain Valve Connection | 1-1/4" NPT Female |
| Insulation | Not available in this size |
| ASME Code Stamp | Section VIII, Division 1; National Board registered; ASME U stamp at 150 psi |
| CRN | Registered |
| Product Weight | 231 lb |
Specifications on this page are taken from Caleffi North America technical brochure 01076/24 NA and the associated submittal and installation documents linked below. Last verified July 2026.
Documentation
Design Resources
Related Products
- Caleffi NA549150A : HydroCal 6" ANSI Flanged, ASME/CRN
- Caleffi NA549150AM : SEP4 6" ANSI Flanged, ASME/CRN
- Caleffi 501502A : MAXCAL Automatic Air Vent 3/4" NPT Female
- Caleffi NA39589 : Ball Valve 3/4" Female-Female
Frequently Asked Questions
What does the Caleffi NA548150A do in a hydronic system?
The Caleffi NA548150A is a hydraulic separator with 6" ANSI B16.5 Class 150 flanged 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 484 gpm and holds 23.2 gallons.
Does the Caleffi NA548150A separate air and dirt?
The NA548150A is a hydraulic separator. It includes a high-capacity automatic air vent to discharge accumulated air and a blowdown drain valve to purge settled impurities, but it does not carry the coalescing dirt element rated to 5 microns or the magnetic element found on the Caleffi HydroCal and SEP4 series.
What flow rate is the Caleffi NA548150A rated for?
Caleffi rates the 6" NA548150A at 484 gpm with a fluid volume of 23.2 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 NA548150A ASME code stamped?
Yes. The NA548150A is designed and built in accordance with Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code, tagged and registered with the National Board of Boiler and Pressure Vessel Inspectors, and stamped for 150 psi working pressure with the ASME U stamp. It is also CRN registered for Canadian projects.
Does the Caleffi NA548150A come with insulation?
No. Caleffi does not offer a pre-formed insulation shell for flanged separators in sizes 5" through 14". Insulation for these vessels is field-fabricated.
- Type:
- Hydraulic Separator
- Separation Functions:
- Hydraulic
- Product Line:
- Hydro Separator
- Series:
- NA548
- Connection Style:
- Flanged
- ASME Code Stamped:
- Yes
- CRN Registered:
- Yes
- Insulation Included:
- No
- Connection Type:
- ANSI Flange
- Connection Size:
- 6 inch
- Max Operating Pressure:
- 150 psi
