Yoshitake OB-3G is a direct-acting temperature regulator valve designed for both heating and cooling applications. It is equipped with an external pressure type bellows that ensures distinguished temperature resistance, making it highly reliable for controlling cold and hot water, oil, refrigerants, and other non-dangerous fluids. The valve features a dual-valve structure that provides a larger flow rate compared to single-valve models, and it utilizes a union type connection screw for easy piping installation.

Features

1. Piping can be easily connected due to a union type connection screw.
2. These temperature regulators do not require any adjusting tool because they are equipped with an adjusting handle which leads to easy adjustment.
3. Since these temperature regulators adopt a dual-valve structure, the flow rate is larger than that of single-valve temperature regulators.
4. Excellent accuracy since special packing is used for spindle gland packing which affects the opening/closing operation of the valve.
5. OB-3G ensures distinguished temperature resistance due to an external pressure type bellows.

Specifications

Feature	Specification
Application (Cooling)	Cold water, Refrigerant
Application (Heated)	Cold and hot water, Oil, Non-dangerous fluid
Max. Pressure (Body)	0.7 MPa
Max. Pressure (Thermal bulb)	1.0 MPa
Maximum Temperature	180°C
Temperature Adjusting Range	15-100°C (For liquid and air)
Ambient Temperature	Set temp. +30°C or less
Material (Body)	Bronze
Material (Valve, valve seat)	Bronze
Material (Valve spindle)	Stainless steel
Material (Bellows)	Phosphor bronze
Material (Thermal bulb)	Stainless steel (with fin for air)
Standard Capillary Length	2 m (Available up to 5 m)
Connection	JIS Rc screwed (union joint)

INFO

• If the ambient temperature is higher than the set temperature or less than 40°C, use the OB-3G (with external pressure type bellows).
• Available with thermal well (SUS304 made or with a PTFE cap) for liquid.

Temperature Adjusting Range

Temperature adjusting range (°C)	Withstand temperature (°C)
15 - 35	50
20 - 40	50
35 - 55	70
40 - 60	90
50 - 70	100
60 - 80	110
70 - 90	120
80 - 100	130

The term "Withstand temperature" means the temperature from pressure resistance of the bellows.

Performance Data

Temperature Accuracy from Set Point

Depending on capillary length (For liquid and air):

• 2m: ± 3.5°C
• 2-3.5m: ± 4°C
• 3.5-5m: ± 4.5°C

(If the preset temperature is higher than 100°C, add ± 1.0°C. The preset temperature error is the maximum temperature width ranging from the time when the valve closes until the time when the valve starts to open, not the value expressing the control width.)

Cv Value and Valve Seat Leakage

Nominal Size	15A	20A	25A	32A	40A
Cv Value	2	2	4	7	10
Valve Seat Leakage	1.5	1.5	1.8	2.4	3.0

(Leakage Unit: steam kg/h, water L/h. Measured under the condition of 0.5 MPa or max. pressure at the temperature of "set temperature - 5°C" for cooling.)

Dimensions and Weights

Nominal size	d	L (mm)	H1 (mm)	H (mm)	Weight (kg)
15A	Rc 1/2	148	55	510	11
20A	Rc 3/4	148	55	510	11
25A	Rc 1	160	60	520	12
32A	Rc 1-1/4	195	60	520	12
40A	Rc 1-1/2	210	65	530	13

Nominal Size Selection Chart (For Water)

How to use the chart: When inlet pressure is 0.3 MPa, outlet pressure is 0.15 MPa, and flow rate is 9 m³/h, first find the intersection point (a) with the differential pressure (∆P) 0.15 MPa (0.3 MPa – 0.15 MPa) before and after valve and the flow rate 9 m³/h. Since this intersection point (a) locates between nominal sizes 32A and 40A, select the larger one, 40A.

Installation and Piping

Installation of Main Unit

1. Install the temperature regulator valve vertically against the horizontal pipe, placing its frame above.
2. Make sure to install a pressure gauge and a strainer bypass pipe in the piping.
3. If the pressure of the heating fluid is higher than the maximum pressure, use the product after reducing the pressure with a pressure reduction valve.
4. Implement the plumbing in a way that does not add excessive load, bending force, vibration, etc. to the main unit.

Installation of Thermal Bulb

1. Avoid bending the capillary tube at a sharp angle, twisting or pulling it with force. Secure the capillary tube not to allow it to touch steam piping or any other high temperature source. The bend radius of the capillary tube should be more than 40 mm.
2. Make sure that more than 3/4 of its total length is in direct contact with the fluid to be heated.
3. Install a thermometer close to the thermal bulb.
4. Make sure that the thermal bulb's joint section does not incline downward and does not become lower than its tip. Plumb it in a way that makes the T mark position of the flange or joint nut come to the top.

Example of Piping

WARNING

• In case of high temperature fluid, do not touch the product directly with bare hands. There is danger of scald.
• Do not fasten the gasket of the product additionally. The gasket may break and external leakage may occur.
• When supplying air or water to the product, make sure to close the stop valves at the front and the rear of the product and remove foreign substances, scale, etc. completely through the bypass pipe.

Adjustment Procedures

TIP

Incorrect adjustment may cause hunting, scale problems or water hammer, and may heavily damage the main parts of the product. Be sure to follow the steps below:

1. Close the stop valves at the front and the rear of the product. Open the bypass stop valve and blow fluid through the bypass line with enough time. After discharging, be sure to close the bypass stop valve.
2. Turn the handle and move the indicator to the desired temperature position on the scale. To raise the temperature, turn the handle counterclockwise (when seen from the top). To lower the temperature, turn it clockwise (when seen from the top). Reading scale is only for reference, so please adjust the temperature by using a thermometer.
3. Slowly open the inlet stop valve to its full open position, and then, open the outlet stop valve little by little to its full open position.
4. Adjust the handle till the desired temperature is obtained while watching the thermometer with enough time.

Structure and Parts

No.	Name of Parts	Material
1	Body	Bronze
2	Bottom Cover	Brass
3	Union Nipple	Bronze
4	Union Nut	Ductile Cast Iron
5	Valve	Phosphor Bronze or Bronze
10	Gland Packing	PTFE
14	Spindle	Stainless Steel
17	Handle	Cast Iron
24	Bellows	Phosphor Bronze
31	Flexible Tube	Copper Tube
33	Thermal Element Pipe	Stainless Steel

(Note: This is a partial list of key components. Refer to the full technical drawing for all 39 parts.)