Yoshitake LD-51 is a self-operated drain valve for gas lines that automatically discharges condensate without external power. Featuring a soft seal structure, it is designed to contribute to a hydrogen society and is suitable for air, other non-dangerous gases, and hydrogen gas (contact for details).

Specifications

Specification	Value
Model	LD-51
Nominal Size	15A
Application	Air, Other non-dangerous gas, Hydrogen gas (*Contact for details)
Working Pressure	0–100 kPa
Working Temperature	5–80°C
Inlet Connection	JIS R 1/2 screwed
Outlet Connection	Hose joint (φ6)

Related Models

The catalog also includes the LD-16 model, which supports higher working pressures (0–1.0 MPa) and is available in nominal sizes from 15A to 25A with a JIS Rc1/4 outlet connection.

Materials and Parts

No.	Part Name	Material
1	Body	Stainless Steel (SUS304)
2	Cover	Stainless Steel (SUS304)
3	Hanger Metal	Stainless Steel (SUS304)
4	Valve Seat	Stainless Steel (SUS304)
5	Valve Disc	FKM
6	Disc Cover	Stainless Steel (SUS304)
7	Lever	Stainless Steel (SUS304)
8	Spring	Stainless Steel (SUS304)
9	Float	PP & FKM (Heat-resistance plastic & Fluororubber)
10	O-ring	FKM
11	Label	Polyester

Dimensions

Maximum Continuous Discharge Capacity

Operation

1. When the product is installed, air exists inside the product and the float is lowered by its own weight, causing the valve disc to remain closed via the lever.
2. When condensate enters the product, the float gains buoyancy and rises, then the valve disc opens via the lever to discharge the condensate.
3. After the condensate is discharged, the liquid level drops, the buoyancy of the float decreases, and the valve disc closes. At this point, condensate (residual water) accumulates as shown in the operating diagram.
4. Thereafter, the operations of steps 2 and 3 are repeated, enabling continuous discharge of the condensate.

Installation and Piping

Installation Precautions

• The product outlet side should be led to a safe location, even if condensate is discharged. Maintain a clearance of at least 50 mm between the end of the tube or piping and the overflow edge of the drainage system.
• Before installing the product, be sure to remove foreign substances and scale from the piping. Prevent seal tape or liquid seal agent from entering the piping. This product cannot be disassembled to remove internal foreign substances.
• Install a strainer (60 mesh) at the inlet side of the product to prevent foreign substances or scale from entering.
• Install a stop valve and union on the inlet side for maintenance and inspection.
• If horizontal piping exists between the condensate outlet of the pressure vessel and the product, install an equalizing pipe connected above the water level of the pressure vessel.
• When installing a separator, connect the product at a position lower than the inlet of the separator.
• Install the product vertically (tolerance angle 5°).
• Tighten the hexagonal part of the body with a wrench. Do not tighten more than necessary (35 N·m).
• Avoid impacts caused by sudden pressure fluctuations, such as water hammer.
• Ensure the outlet piping is arranged in a way that prevents backflow.
• If there is a risk of freezing, apply insulation to prevent freezing, as residual water accumulates inside.

Maintenance and Troubleshooting

Maintenance Precautions

• Maintenance and inspection must be performed by a professional.
• Be sure to completely release the internal pressure of the product, piping, and equipment during maintenance and inspection. In the case of hot fluid, cool the product body until it can be touched with bare hands.
• This product cannot be disassembled.

Daily Inspections

Please carry out daily inspections to maintain product functionality and performance.

Item	How to inspect	Actions to be taken
Working state	Confirm that condensate is being discharged. (If no condensate is present internally, the valve will remain closed.)	See Troubleshooting
Valve seat leakage	Check visually	See Troubleshooting
Outside leakage	Check visually	See Troubleshooting

Note: Although service life may vary depending on usage conditions, it is recommended to replace the product every 3 to 5 years, along with daily inspections.

Troubleshooting

Trouble	Cause	Remedy
Condensate is not discharged.	1. Stop valve at inlet or outlet is closed. 2. Pressure difference is too high. 3. Clogging of the valve seat hole due to foreign substances. 4. The float is damaged. 5. Damaged or deformed due to abnormal pressure increase caused by freezing or water hammer, etc.	1. Open the stop valve. 2. Reduce to appropriate pressure difference. 3. Replace the product and install a strainer on the inlet side. 4. Replace the product. 5. Replace the product and use it within the working pressure range.
Condensate does not stop discharging.	1. Foreign substances or damage exist between valve disc and valve seat. 2. Product specifications are insufficient for usage condition.	1. Replace the product. 2. Recheck the selection of the product.
Outside leakage.	1. Damaged or Deformed due to abnormal pressure increase caused by freezing or water hammer, etc. 2. O-ring is damaged.	1. Replace the product and use it within the working pressure range. 2. Replace the product.