The Caleffi 304050A is a Vacu-Stop vacuum relief valve with a 3/4 in NPT male connection, admitting air to prevent vacuum conditions that could siphon water from and damage water heaters and storage tanks.
Product data compiled from Caleffi North America technical documentation. Last reviewed July 2026.
Key Features
Prevents Vacuum Siphoning
Automatically admits air to break a vacuum that could siphon water from tanks and damage water heaters.
Water Heater & Tank Protection
Ideal for water heaters, supply tanks and low-pressure steam service; complies with ANSI Z21.22 and CSA 4.4.
Lead-Free / NSF Certified
DZR low-lead brass, certified to NSF/ANSI/CAN 61 and NSF/ANSI/CAN 372 for potable water.
3/4 In Npt Male Connection
3/4 in NPT male connection.
Technical Data
| Function | Vacuum relief valve |
|---|---|
| Connection | 3/4 in NPT male |
| Body material | DZR low-lead brass |
| Maximum operating pressure | 200 psi |
| Medium temperature range | 32 - 250 °F |
| Lead-free compliance | NSF/ANSI/CAN 61 and NSF/ANSI/CAN 372 |
Documentation
Technical brochureRelated Products
Frequently Asked Questions
It is a vacuum relief valve that admits air to prevent a vacuum from forming, which could siphon water out of a tank or water heater and cause damage.
On water heaters, supply tanks and low-pressure steam equipment; it complies with ANSI Z21.22 and CSA 4.4.
Yes, the body is DZR low-lead brass certified to NSF/ANSI/CAN 372.
This model has a 3/4 in NPT male connection.
- Type:
- Vacuum Relief Valve
- Series:
- Vacu-Stop
- Connection Type:
- NPT Threaded
- Connection Size:
- 3/4 in
