6-9-p0027-0080-vx21_en.pdf - 第42页

C , b Indication by international standard S Cv Cv Conformed standar d ISO 6358: 1989 JIS B 8390: 2000 JIS B 8390: 2000 Equipment: JIS B 8379, 8381-1, 8381-2 IEC60534-1: 2005 IEC60534-2-3: 1997 JIS B 2005-1: 2012 JIS B 2…

1. Material

NBR: Nitrile rubber

FKM: Fluororubber

EPDM: Ethylene propylene rubber

2. Oil-free treatment

The degreasing and washing of wetted parts

3. Symbol

In the symbol ( ), when the valve is closed, flow is blocked

from port 1 to port 2. However, if the pressure in port 2 is higher

than port 1, the valve will not be able to block the fluid and it will

flow from port 2 to port 1.

Pressure Terminology

1. Maximum operating pressure differential

The maximum pressure differential (the difference between

the inlet and outlet pressure) which is allowed for operation.

When the outlet pressure is 0 MPa, this becomes the maxi-

mum operating pressure.

2. Minimum operating pressure differential

The minimum pressure differential (the difference between the

inlet pressure and outlet pressure) required to keep the main

valve fully open.

3. Maximum system pressure

The maximum pressure that can be applied inside the pipe-

lines (line pressure).

[The pressure differential of the solenoid valve portion must

not exceed the maximum operating pressure differential.]

4. Withstand pressure

The pressure in which the valve must be withstood without a

drop in performance after holding for one minute under pre-

scribed pressure and returning to the operating pressure

range. [value under the prescribed conditions]

Electrical Terminology

1. Apparent power (VA)

Volt-ampere is the product of voltage (V) and current (A).

Power consumption (W): For AC, W = V·A·cos θ.

For DC, W = V·A.

Note) cos θ shows power factor. cos θ ≈ 0.9

2. Surge voltage

A high voltage which is momentarily generated by shutting off

the power in the shut-off area.

3. Degree of protection

A degree defined in the “JIS C 0920: Waterproof test of elec-

tric machinery/appliance and the degree of protection against

the intrusion of solid foreign objects.”

Verify the degree of protection for each product.

Second

characteristic

numeral

First

characteristic

numeral

First Characteristics:

Degrees of protection against solid foreign objects

Non-protected

Protected against solid foreign objects of 50 mmø and greater

Protected against solid foreign objects of 12 mmø and greater

Protected against solid foreign objects of 2.5 mmø and greater

Protected against solid foreign objects of 1.0 mmø and greater

Dust-protected

Dust-tight

Example) IP65: Dust-tight, Water-jet-proof type

“Water-jet-proof type” means that no water intrudes

inside an equipment that could hinder from operating

normally by means of applying water for 3 minutes in

the prescribed manner. Take appropriate protection

measures, since a device is not usable in an environ-

ment where a droplet of water is splashed constantly.

Second Characteristics:

Degrees of protection against water

—

VX21/22/23 Series

Glossary of Terms

Others

Flat Terminal

Dripproof type 1

Dripproof type 2

Rainproof type

Splashproof type

Water-jet-proof type

Powerful water-jet-proof type

Immersible type

Submersible type

Non-protected

Protected against vertically falling water drops

when enclosure tilted up to 15°

Protected against rainfall when enclosure tilted up to 60°

Protected against splashing water

Protected against water jets

Protected against powerful water jets

Protected against the effects of temporary immersion in water

Protected against the effects of continuous immersion in water

Flat terminal/Electrical connection size of molded coil

0.8

3.4

6.35

Chamfer

VX2

VXK

VXD

VXZ

VXS

VXB

VXE

VXP

VXR

VXH

VXF

VX3

VXA

VX2

C, b

Indication by

international standard

Conformed standard

ISO 6358: 1989

JIS B 8390: 2000

Equipment: JIS B 8379, 8381-1, 8381-2

IEC60534-1: 2005

IEC60534-2-3: 1997

JIS B 2005-1: 2012

JIS B 2005-2-3: 2004

Equipment: JIS B 8471, 8472, 8473

ANSI/(NFPA)T3.21.3 R1-2008

Table (1) Indication of Flow Rate Characteristics

—

Pneumatic

equipment

Process fluid

control

equipment

Corresponding

equipment

Other

indications

Indication of flow rate characteristics

The flow rate characteristics in equipment such as a solenoid valve, etc. are indicated in their specifications as

shown in Table (1).

Pneumatic equipment

2.1 Indication according to the international standards

(1) Conformed standard

ISO 6358: 1989

: Pneumatic fluid power—Components using compressible fluids—

Determination of flow rate characteristics

JIS B 8390: 2000 : Pneumatic fluid power—Components using compressible fluids—

How to test flow rate characteristics

(2) Definition of flow rate characteristics

The flow rate characteristics are indicated as a result of a comparison between sonic conductance C and

critical pressure ratio b.

Sonic conductance C

Value which divides the passing mass flow rate of an equipment in a choked flow

condition by the product of the upstream absolute pressure and the density in a

standard condition.

Critical pressure ratio

b : Pressure ratio (downstream pressure/upstream pressure) which will turn to a choked

flow when the value is smaller than this ratio.

Choked flow : The flow in which the upstream pressure is higher than the downstream pressure and

where sonic speed in a certain part of an equipment is reached.

Gaseous mass flow rate is in proportion to the upstream pressure and not dependent

on the downstream pressure.

Subsonic flow : Flow greater than the critical pressure ratio

Standard condition

: Air in a temperature state of 20°C, absolute pressure 0.1 MPa (= 100 kPa = 1 bar),

relative humidity 65%.

It is stipulated by adding the “(ANR)” after the unit depicting air volume.

(standard reference atmosphere)

Conformed standard: ISO 8778: 1990 Pneumatic fluid power—Standard reference

atmosphere, JIS B 8393: 2000: Pneumatic fluid power—Standard reference atmosphere

(3) Formula for flow rate

It is described by the practical units as following.

When

P2 + 0.1

————

≤ b, choked flow

P1 + 0.1

293

Q = 600 x C (P1 + 0.1)

————

·····························································(1)

273 + T

When

P2 + 0.1

———— > b, subsonic flow

P1 + 0.1

P2 + 0.1

———— – b

P1 + 0.1

Q = 600 x C (P1 + 0.1) 1 –

—————— ———— ····························

(2)

1 – b

293

273 + T

VX21/22/23 Series

Solenoid Valve Flow Rate Characteristics

(How to indicate flow rate characteristics)

ød2

ød1

3d3

3d210d23d110d1≥10d3

ød3≥3d1

: Air flow rate [L/min (ANR)]

: Sonic conductance [dm

/(s·bar)], dm

(Cubic decimeter) of SI = L (liter).

: Critical pressure ratio [—]

: Upstream pressure [MPa]

: Downstream pressure [MPa]

: Temperature [°C]

Note) Formula of subsonic flow is the elliptic analogous curve.

Flow

rate characteristics are shown in Graph (1) For details, please use the calculation software available from SMC website.

Example)

Obtain the air flow rate for P1 = 0.4 [MPa], P2 = 0.3 [MPa], T = 20 [°C] when a solenoid valve is performed in

C = 2 [dm

/(s·bar)] and b = 0.3.

293

According to formula 1, the maximum flow rate = 600 x 2 x (0.4 + 0.1) x ————— = 600 [L/min (ANR)]

273 + 20

0.3 + 0.1

Pressure ratio = ————— = 0.8

0.4 + 0.1

Based on Graph (1), it is going to be 0.7 if it is read by the pressure ratio as 0.8 and the flow ratio to be b = 0.3.

Hence, flow rate = Max. flow x flow ratio = 600 x 0.7 = 420 [L/min (ANR)]

(4) Test method

Attach a test equipment with the test circuit shown in Fig. (1) while maintaining the upstream pressure to a

certain level which does not go below 0.3 MPa. Next, measure the maximum flow to be saturated in the first

place, then measure this flow rate at 80%, 60%, 40%, 20% and the upstream and downstream pressure. And

then, obtain the sonic conductance C from this maximum flow rate. In addition, calculate b using each data of

others and the subsonic flow formula, and then obtain the critical pressure ratio b from that average.

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Equipment

C, b

b = 0.1

0.2

0.5

0.6

0.3

0.4

Pressure ratio (

P2 + 0.1) / (P1 + 0.1)

Air

supply

Pressure control

equipment

Thermometer

Pressure gauge or

pressure convertor

Differential pressure gauge or

differential pressure converter

Flow control

valve

Filter

Pipe for measuring

temperature

Pipe for

measuring

pressure in the

upstream side

Pipe for

measuring

pressure in the

downstream side

Equipment

for test

Shut off

valve

Flow meter

Fig. (1) Test circuit based on ISO 6358: 1989, JIS B 8390: 2000

Graph (1) Flow rate characteristics

Flow rate ratio

Example

Solenoid Valve Flow Rate Characteristics

VX21/22/23 Series

VX2

VXK

VXD

VXZ

VXS

VXB

VXE

VXP

VXR

VXH

VXF

VX3

VXA

VX2