Fan and Heater
SELF-OPERATED MODULATING VALVES
Johnson Controls, Inc.
Control Products Division
1302 East Monroe Street
Goshen, IN 46526
Series V50
For Outdoor Crop Dryer Service
Installation and Operation
Instructions
Application
These valves control the flow of gas on natural or LP gas fired outdoor crop dryers to maintain desired drying air temperature. Changes in air temperature at the sensing bulb cause the valve to modulate the gas supply to the main burner.
CAUTION: Valves are for outdoor crop dryer service only. Not for use on applications of any other kind.
All Series V50 valves are designed for use only as operating devices. Where system closure, improper flow or loss of pressure due to valve failure can result in personal injury and/or loss of property, a separate pressure relief or safety shutoff valve, as applicable, must be added by the user.
Operation
LP Gas Application
These valves are normally located on the crop dryer gas manifold between the pressure regulating valve and the burner orifice. They are used on vapor withdrawal systems or on liquid withdrawal systems using a direct or indirect vaporizer. They should not be used as a expansion valves (handling liquid LP) on straight liquid withdrawal systems.
A pressure regulating valve is required to maintain uniform inlet pressure to the V50 modulating valve because the tank pressure varies considerably due to changes in tank ambient temperature.
The recommended setting for the pressure regulating valve is no higher than 30PSIG (207 kPa) as in many
Figure 1 | Figure 2 |
Modulating Value V50A | Modulating Value V50B |
instances the outside temperature will not be high enough to provide the regulating valve with pressure above this value. The maximum working pressure for V50
As the modulating valve provides only a portion of the pressure drop, the maximum firing rate (valve wide open) is determined by the setting of the pressure regulator and the size of the burner orifice.
Installation
Follow original equipment manufacturer's installa- tion instructions, if provided.
CAUTION: The valve should not be installed on lines where line pressure excedds 30 PSIG (207 kPa). When there is a possibility of pressures over 30 PSIG, provide an overpressure or alarm control. The temperature at the sensing bulb must not exceed maximum valve range shown on the nameplate by more than 20F° (10C°). The maxi- mum ambient temperature around the valve body must nots exceed 175°F (79°C).
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