225 Auto-Soft Flow Actuated Check Valves

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Overview

The Series 225 Auto-Soft is a flow-actuated check valve used for throttling roughing pumps during initial evacuation. Auto-Soft check valves close very quickly at the start of system evacuation and open automatically upon reaching a set pressure differential. This leaves the pumping line open for the balance of the pumping process.

NW40 - NW50
Operates automatically without electrical or other external power
Reduces particulate contamination by reducing system turbulence during venting

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Products

		Compare	Description	Compatibility	sortOrder	rankScore	ranking	Drawings, CAD & Specs		Port Size	Availability	Featured Item	Price		Brand
		225-0040 Check Valve, Flow Actuated, NW40 Size, Auto-Soft $260 4 Weeks	225-0040 Check Valve, Flow Actuated, NW40 Size, Auto-Soft	UNIVERSAL	0.0	1.0	0.0		0.0	NW40	4 Weeks		$260
		225-0050 Check Valve, Flow Actuated, NW50 Size, Auto-Soft $290 2 Weeks	225-0050 Check Valve, Flow Actuated, NW50 Size, Auto-Soft	UNIVERSAL	0.0	1.0	0.0		0.0	NW50	2 Weeks		$290

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Specifications

Type

Check Valve for Automatic Soft Starts
O-ring

Viton®
Operating Temperature

100°C max.
Tube Outer Diameter

NW40, NW50
Required Clearance

0.3 - 1.0 inches, depending on configuration
Spring Material

Elgiloy®
Closing Flow

NW40: 6 CFM/sec, NW50: 12 CFM/sec

Ring, Tabs, Stop & Axel Material

Type 304 stainless steel
Vane Material

Inconel® 625
Bearing Material

Teflon®
Closing Time

NW40: 10 ms, NW50: 12 ms
Opening Pressure

NW40: 2 Torr, NW50: 3 Torr
Pumpdown Time

Typical increase in pumpdown time is 3 times.
Times were measured using a pump capacity of 27 CFM for NW 40, 70 CFM for NW 50 and a volume of 100 liters.

Features

Automatic Soft Starts

Auto-Soft has a vane that pivots about an off-center axis. A pair of coil springs hold the vane open when the pressure differential is low enough. When the roughing system goes into operation, the initial flow closes the vane assembly, automatically throttling the roughing pump. Initial pumpdown occurs through small openings around the vane. This reduces the effective pumping speed, which minimizes turbulence and extends pumpdown time. When the pressure differential reaches the level determined by the springs, the springs open the vane and full pumping speed is restored. When installing the Auto-Soft, adequate space is needed, the amounts are listed in the specifications table. The user can adjust the closed conductance of the valve over a limited range by bending tabs adjacent to the vane. The Auto-Soft should be installed between the vacuum system and the roughing valve. Trapping of contamination before the Auto-Soft will help to ensure a long life.

Applications

In the semiconductor, thin film, and other industries, Auto-Soft replaces pressure controlled bypass valves to provide a soft start. The soft start then reduces turbulence in the vacuum system. Particles resident in the system are not stirred up and the work in progress is not damaged. During pumpdown, the pressure differential across products in the system can displace or break them. Auto-Soft slows the pumpdown process, eliminating the wide pressure differential. Auto-Soft can be used when venting a system. Used with a vent valve, Auto-Soft will reduce turbulence and extreme pressure differentials while venting the system. Auto-Soft can be used in many other applications. When used with potting compounds, Auto-Soft prevents excessive foaming. Auto-Soft used in a vacuum glove box avoids the rupture of filters. When used on a system with a mechanical pump, Auto-Soft reduces exhaust oil mists.