The Caleffi 551004A is a DISCALAIR air vent with a 3/4" male NPT inlet and 1/2" female NPT connection. A float-operated high-discharge vent, it releases large volumes of air during system filling and continuously during operation.
Best for automatic air release at system high points.
Specifications sourced from Caleffi North America technical literature. Last reviewed July 2026.
Key Features
High Discharge Capacity
Releases large amounts of air quickly, making it suited to system fill, purge and air separator service.
System Protection
Continuous automatic air release helps reduce oxygen-driven corrosion, trapped-air noise in emitters and cavitation at circulator pumps.
Technical Specifications
| Function | Automatic float air vent |
| Series | Caleffi DISCALAIR |
| Connection | 3/4 in NPT male x 1/2 in NPT female |
| Body material | Brass |
| Maximum operating pressure | 150 psi |
| Maximum air discharge pressure | 150 psi |
| Maximum discharge rate | 4.5 SCFM |
| Medium temperature range | 32 - 230 °F |
| Shipping Weight | 0.8 lb |
Documentation
Related Products
- Caleffi 502420 : ROBOCAL Air Vent 1/4" Metric Thread
- Caleffi 502630 : ROBOCAL Air Vent 3/8" Metric Thread
- Caleffi 502640 : ROBOCAL Air Vent 1/2" Metric Thread
- Caleffi 337221A : Manual Air Vent 1/4" NPT Threaded
Frequently Asked Questions
What does Caleffi 551004A do?
Caleffi 551004A is an air vent in the Caleffi DISCALAIR range. It automatically releases air that accumulates in the system, helping prevent oxygen-driven corrosion, trapped-air noise and pump cavitation.
What connection does Caleffi 551004A use?
It is supplied with a 3/4" male NPT inlet and 1/2" female NPT connection. Other sizes and connection styles in the DISCALAIR range are listed under Related Products.
What are the pressure and temperature limits of Caleffi 551004A?
Maximum operating pressure is 150 psi, over a medium temperature range of 32 - 230 °F.
What is the warranty on Caleffi 551004A?
Caleffi covers this product under its standard two-year limited warranty against defects in material and workmanship from the date of shipment. ZOT Supply is an authorized Caleffi distributor.
- Product Type:
- Air Vent
- Series:
- DISCALAIR
- Connection Type:
- NPT Threaded
- Connection Size:
- 3/4 in
- Max Operating Pressure:
- 150 psi
- Medium Temperature Range:
- 32 - 230 deg F
- Body Material:
- Brass
