The Yoshitake TAV-4 Air Vent Valve with Vacuum Breaker is primarily installed at the top of water supply vertical pipes in housing complexes and similar applications. This valve exhausts air from vertical piping while water is filling to reduce air discharge from faucets, continuously exhausts accumulated air during normal use to lessen water running resistance, and sucks air from outside the piping to destruct any negative pressure generated inside the system.

Features

• Rapid Air Intake Performance: Meets Nagoya City Waterworks & Sewerage Bureau and Urban Renaissance Agency standards (equal to Swedish standard) where one 20A product is appropriate for a 50A vertical pipe. Under Bureau of Waterworks, Tokyo Metropolitan Government standards, one 25A product is appropriate for a 75A vertical pipe.
• Initial Exhaust Function: Exhausts air from the water supply vertical pipe when filled with water, reducing air blowout from faucets.
• Cold Area Usable: Complies with the cold resistance performance standard set by the Ministry of Health, Labor and Welfare, Japan.
• Flexible Connection: The pipe end core connects to the pipe connection port, allowing the product to rotate 360 degrees so the guide pipe connection port can face any required direction.

Specifications

Application	City water (clean water)
Working pressure	0.05-1.0 MPa
Intake air quantity (under the pressure difference of 2.9 kPa)	20A: 15.1 L/sec 25A: 23.4 L/sec
Working temperature	0-40°C (no freeze condition)
Body	Cast bronze (NPb-treated)
Float	Synthetic resin
Exhaust Packing	Synthetic rubber

Dimensions and Weight

Nominal size	d1	d2	H	H1	W	L	Weight
20A	JIS R 3/4	JIS Rc 1	151	130	φ76	49.5	1.2 kg
25A	JIS R 1	JIS Rc 1	153	132	φ76	49.5	1.2 kg

Performance

Intake/Exhaust Performance

Exhaust Performance Under Pressure

INFO

The values read from the charts should be used as a reference. Ensure a safety factor of at least 20% due to potential fluctuations in piping or usage conditions.

Structure

No.	Part Name	Material	No.	Part Name	Material
1	Bonnet	-	8	Ring	Stainless Steel
2	O ring	NBR	9	Exhaust packing	EPDM
3	Body	-	10	Exhaust Spring	Stainless Steel
4	Float body	-	11	Lever board	POM
5	Float shaft	PE	12	Intake valve	POM
6	O ring	NBR	13	Cover	Bronze
7	O ring	NBR

Operation

1. Rapid Air Intake

When internal pressure of the piping drops below atmospheric pressure due to water stoppage or draining, the product's internal pressure also drops. The intake valve lowers, starting air intake.

2. Initial Exhaust

The intake valve is lowered by the weight of the float until water fills the piping and enters the product, exhausting a large quantity of air. When air decreases and water enters, the intake valve floats and closes the opening.

3. Normal State

When filled with water, the exhaust valve is closed by water pressure and exhaust spring force. The intake valve is closed by water pressure alone. Because the exhaust valve is independent of the float, its position remains stable despite water pressure fluctuations.

4. Exhaust Under Pressure

When air enters the water-filled body, the water level lowers, causing the float to descend. The float's weight is applied to the lever board. Once this overcomes the pressure difference and the exhaust spring force, the exhaust valve opens. As air is exhausted and water re-enters, the float rises, removing the weight from the lever board, and the exhaust spring closes the valve.

Selection Guide

Intake/exhaust valves must be selected based on the intake air quantity required for negative pressure destruction per the nominal size of vertical water pipes.

Nominal size of vertical pipe	Nagoya City Waterworks & Sewerage Bureau / Urban Renaissance Agency Standard (L/sec)	Bureau of Waterworks, Tokyo Metropolitan Government Standard (L/sec)	Selection of TAV-4
20A	1.5	1.5	1 piece of TAV-4 20A
25A	2.5	2.5	1 piece of TAV-4 20A
32A	4.0	3.5	1 piece of TAV-4 20A
40A	7.0	5.5	1 piece of TAV-4 20A
50A	14.0	9.0	1 piece of TAV-4 20A
75A	33.4 (2004 L/min)	15.5	1 piece of TAV-4 25A (Tokyo standard) / 2 or more pieces (Nagoya standard)
100A	-	25.0	2 or more pieces
150A	-	53.0	2 or more pieces

Piping Example

Install the product to satisfy or exceed the required intake air quantity.

• Piping A: Requires one 20A product (max pipe diameter 50A).
• Piping B: Requires one 25A product (max pipe diameter 75A, Tokyo standard).
• Piping C & D: Examples requiring multiple pieces. Ensure smooth air flow at branches.

Installation Procedure

Guide pipe use: 25A steel pipe or 25A PVC is allowed. Total length should be 1 m or less. Only one elbow is permitted. Stop valve must be a gate valve or full-bore ball valve (not a globe valve) with a nominal diameter equal to or larger than the TAV-4.

Precautions for Installation

• Install the product at least 300 mm above the overflow line of the water supply equipment or container.
• Do not connect an earth to the product or piping, as it may cause corrosion.
• Be sure to connect a guide pipe (25A or larger) to the exhaust outlet and lead it to a drain hopper, maintaining at least 50 mm clearance between the pipe end and the overflow line.
• The guide pipe must go down from the product; upward piping is not allowed.
• Install the product perpendicularly (within 5 degrees from vertical) in locations where air accumulates.
• Take measures (insulation, heating) to prevent freezing, as it may cause malfunction.
• When installing the product, strictly apply tools (spanner, chain wrench, pipe wrench) only on the four grippers located directly above the screwed connection part to avoid damage.

Operating Notes

• Water may spray out during exhausting; this is normal.
• Drain water during low winter temperatures or long periods of non-use to prevent freezing and rust damage.
• Open the fluid supply valve slowly to avoid water hammer damage.
• Water may drain out if the system pressure drops below 0.05 MPa, which is not a failure.