Emerson Fluid Chiller Anleitung zur Fehlerbehebung PDF herunterladen (Seite 27)

Solenoid Valves

Emerson Climate Technologies

Figures 1A and 1B show a simple schematic

of a Direct Acting Solenoid Valve in operation.

2. Pilot Operated Valve

The pilot operated solenoid valve uses a combination

of the solenoid coil and the line pressure to operate. In

this type valve the plunger is attached to a needle valve

covering a pilot orice rather than the main port. The

line pressure holds an independent piston or diaphragm

closed against the main port. See gures 2a and 2b.

When the coil is energized, the plunger is pulled into the

center of the coil, opening the pilot orice. Once the pilot

port is opened, the line pressure above the diaphragm is

allowed to bleed off to the low side or outlet of the valve,

thus relieving the pressure on the top of the diaphragm.

The inlet pressure then pushes the diaphragm up and

off of the main valve port and holds it there allowing full

uid ow. When the coil is de-energized, the plunger

drops and closes the pilot orice. Pressure starts to build

up above the diaphragm by means of a bleed hole in the

piston diaphragm until it and the diaphragm’s weight and

spring cause it to close on the main valve port. A pilot

operated solenoid valve requires a minimum pressure

difference of several pounds between inlet and outlet to

operate.

Types of Solenoids

There are different types of solenoid valves for differ-

ent applications. The three main types of valves are the

2-way, 3-way, and 4-way valves. The 2-way valve is the

most common.

2-Way Valves

The 2-way valve controls uid ow in one line. It has

an inlet and an outlet connection. This valve can be of

the direct acting or pilot operated type of valve depend-

ing on the need. When the coil is de-energized, the 2-

way valve is normally closed. Although normally closed

is the most widely used, two-way and three-way valves

are manufactured to be normally open when the coil is

de-energized. See Figure 3 for an example of a 2-way

valve.

Figures 2A and 2B show a simple schematic

of a Pilot Operated Solenoid Valve in operation.

NOTE: 2-way valves are usually designed to have

ow in one direction only. Some valves may be modied

to have ow in both directions. A “bi-ow” kit must be

used.

Figure 3

FIG. 1A DE-ENERGIZED

FIG. 1B ENERGIZED

FIG. 2A DE-ENERGIZED

FIG. 2B ENERGIZED

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 71 72

Kommentare zu diesen Handbüchern

Keine Kommentare

Emerson Fluid Chiller Anleitung zur Fehlerbehebung Seite 27

Kommentare zu diesen Handbüchern

Verwandte Produkte und Handbücher für Nein Emerson Fluid Chiller