3
■
EPDT-213b
■
3. Operation
■
OB-30, OB-30U
Heating the thermal bulb [20] makes its inner pressure rise, while cooling it makes the pressure lower. The
bellows [14] expands/contracts responding to the change in the internal pressure that is transmitted through
the capillary tube [21], and this allows the valve [4] open/close.
When the temperature of the thermal bulb rises, the bellows expands and applies lifting force to the spindle [7] to
close the valve. When the temperature of the bulb lowers, the downward force applied to the spindle by the spring
[11] opens the valve.
The set temperature can be adjusted by turning the handle [12] to change the load of the spring.
No.
Part name
1 Body
2 Spring chamber
3 Disc
4 Valve
5 Valve seat
6 Balance bellows
7 Spindle
8 Nut
9 Guide
10 Guide
11 Spring
12 Handle
13 Bellows follower
14 Bellows
15 Ring
16 Gasket
17 Bolt
18 Bushing
19 Washer of packing
20 Thermal bulb
21 Capillary tube
*22 Packing
The parts marked “*” are
available as consumable
supply.
Thermal bulb with Thermal
well (stainless steel) does not
need bushing for thermal
bulb.
OB-30
OB-30U
