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; warranty per Caleffi North America Limited Warranty. 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.
Technical Data
| Function | Vacuum relief valve |
|---|---|
| Connection | 3/4 in NPT male |
| Body material | DZR low-lead brass |
| Maximum working pressure | 200 psig water; 15 psig steam |
| 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
