Variable Leak Valve Model 951-5106 User Manual 87-400-085-01 (D) 05/2011
Notices © Agilent Technologies, Inc. 2011 No part of this manual may be reproduced in any form or by any means (including electronic storage and retrieval or translation into a foreign language) without prior agreement and written consent from Agilent Technologies, Inc. as governed by United States and international copyright laws. Manual Part Number Publication Number: 87-400-085-01 (D) Edition Edition 05/2011 Printed in ITALY Agilent Technologies Italia S.p.A. Vacuum Products Division Via F.
Variable Leak Valve Variable Leak Valve Variable Leak Valve User Manual / 87-400-085-01 (D) 3/36
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Contents Contents 1 Instructions for Use 7 Safety Information 9 General 10 Variable Leak Valve Outline 13 Flange Connection 14 Inlet Gas Connection 14 Use 15 To Establish a New Stop Position16 To Set Stop Position at any Leak Rate 17 Operating at Low Leak Rates 17 Changes in Leak Rate with Variation in Room Temperature 18 Bakeout Procedure 18 To Use as a Roughing Valve 19 Adjustment of Handle Position 20 If Valve Will not Close Leak-Tight21 Lubrication Instructions 24 Loss of Sensitivity at High
Contents 6/36 Variable Leak Valve User Manual / 87-400-085-01 (D)
Variable Leak Valve User Manual 1 Instructions for Use Safety Information General 9 10 Variable Leak Valve Description 11 The Valve is Shipped in a Closed, LeakTight Condition.
1 Instructions for Use Safety Information If Valve Will not Close Leak-Tight 21 Disassemble 21 Inspect and Clean Sapphire 22 Inspect and Clean Valve Body 22 Inspect and Clean Gasket Assembly 23 Re-Install Sapphire Assembly 23 Re-Install Gasket Assembly 24 Leak-Check and Adjust Closure 24 Lubrication Instructions 24 Loss of Sensitivity at High Leak Rates 26 Disposal 27 Replacement Parts Accessories 8/36 28 30 Variable Leak Valve User Manual / 87-400-085-01 (D)
1 Instructions for Use Safety Information Safety Information This equipment is destined for use by professionals. The user should read this instruction manual and any other additional information supplied by Agilent before operating the equipment.
1 Instructions for Use General General The variable leak valve can be added to any vacuum system to establish an adjustable leak. It offers unprecedented control sensitivity and stability with leak rates as small as 1 x 10-10 Torr-litres per second. Leak rate adjustment is controlled with knurled knobs. The entire valve, including the drive mechanism, is bakeable to 450°C in either the open or closed position.
1 Instructions for Use General Variable Leak Valve Description The variable leak valve includes a movable piston with an opticallyflat sapphire that meets a captured metal gasket (see the following figure). This forms a seal completely free from friction, seizing, and shear. The sapphire’s movement is controlled through a threaded shaft-and-lever mechanism having a mechanical advantage of 13,000 to 1.
1 Instructions for Use General Variable Leak Valve Specifications Tab. 1 Minimum leak rate Rate of change of leak Vacuum range Temperature range Inlet gas pressure Gasket life Material Weight 12/36 1 x 10-9 Torr-litres/sec. in normal operation; 1 x 10-10 Torr-litres/sec.
1 Instructions for Use Variable Leak Valve Outline Variable Leak Valve Outline The outline dimensions for the variable leak valve are shown in the following figure.
1 Instructions for Use Flange Connection Flange Connection The valve is shipped in a closed, leak-tight position, lubricated and ready for installation. The ConFlat flange on which the variable leak valve is mounted mates with any 2 /4 inch O.D. ConFlat flange. 1. Place a new copper gasket (Agilent part no. 953-5014) between the two ConFlat flanges. 2. Lubricate and install bolts and nuts. Use Fel-Pro C-100 high temperature lubricant on screw threads and under the nuts. 3.
Instructions for Use Use 1 Use WARNING! The main danger of explosion in vacuum equipment occurs during backfilling from pressurized gas cylinders. Explosions cause flying debris which may cause serious personal injury or death and destroy equipment. The following precautions must be exercised when admitting gas into a vacuum system: CAUTION! 1. Check that the leak valve is in the closed position before admitting gas into the backfill line. 2.
1 Instructions for Use To Establish a New Stop Position The valve is received in a closed, leak-tight position. The adjusting knurled knobs are tightened against the handle. During normal operation, the knobs are locked together with respect to the fine-drive screw. To open a leak, turn both knobs together a minimum of two full turns counterclockwise. To close a leak, turn the knobs together until the collar botts against the handle (the stop position has been reached).
1 Instructions for Use To Set Stop Position at any Leak Rate To Set Stop Position at any Leak Rate The stop position can be adjusted to provide any desired leak rate. NOTE 1. Open the valve to the desired leak rate as determined by a leak detector, vacuum gauge, or other experimental means. 2. Loosen the knobs from each other without allowing the fine-drive screw to turn. 3. Turn the inner knob clockwise until the collar stops against the handle.
1 Instructions for Use Changes in Leak Rate with Variation in Room Temperature Changes in Leak Rate with Variation in Room Temperature Changes in room temperature will cause changes in leak rate - as the temperature rises, the leak rate increases. A leak setting should be made in the range of interest and then mild heat applied to raise the temperature of the valve to the maximum expected value.
1 Instructions for Use To Use as a Roughing Valve Bakeout in Closed Position a The valve must be overdriven three turns past closure (normal setting is two turns) to compensate for differential expansion of materials during bakeout. b To prepare the valve for bakeout, follow the procedure described in para. “To establish a new stop position” with the following exceptions: in steps 5 and 6, substitute "three turns" for the "two turns" specified.
1 Instructions for Use Adjustment of Handle Position Adjustment of Handle Position As described previously, continual reduction in gasket height necessitates resetting of the stop position and eventual readjustment of handle position. When the angle between the handle and body at point of closure has changed from its original parallel (approximate) position to an angle of +/-5°, the valve should be readjusted.
1 Instructions for Use If Valve Will not Close Leak-Tight If Valve Will not Close Leak-Tight If the valve is not leak-tight across the sapphire-gasket seal after the knobs have been turned to the stop position, one of several problems may be the cause. 1. The gasket has been compressed and the stops must be reset. 2. The valve, sapphire, and/or gasket are contaminated and need cleaning. 3. The gasket is scratched, nicked, or compressed beyond further use and must be replaced. 4.
1 Instructions for Use If Valve Will not Close Leak-Tight e Turn the valve and tool upside down and turn the tool counterclockwise to remove the sapphire assembly. Four full turns will disengage the threads. f Maintain the upside down position of valve and tool, and lower the tool and sapphire assembly from the valve. Inspect and Clean Sapphire a Check the sapphire to be sure that it has no cracks or chips. Any fractures will require replacement of the sapphire assembly.
1 Instructions for Use If Valve Will not Close Leak-Tight CAUTION! Do not use compressed air to blow out the valve. The possible high content of particles, water vapour, and oil will contaminate the valve. Re-cleaning and possible gasket replacement may then be required. Inspect and Clean Gasket Assembly a Inspect the copper alloy gasket to be sure that it is clean, smooth, free of oxide, and protrudes above the surface of the gasket collar by at least 0.002 inch.
1 Instructions for Use Lubrication Instructions CAUTION! Do not overtighten the sapphire assembly with the removal tool. Heavy tightening can cause the tool to raise a burr in the slots of the sapphire assembly. These burrs can prevent subsequent removal of the sapphire assembly from the valve. Re-Install Gasket Assembly NOTE a To avoid contamination, hold the valve in the upright position. Install the gasket assembly and tighten finger-tight. b Tighten the gasket assembly to 22 to 24 ft.-lbs.
1 Instructions for Use Lubrication Instructions 1. Open the valve by turning both knobs four counterclockwise turns. 2. Withdraw the two Phillips head screws on the upper part of the valve body and remove the cover. 3. Remove the roughing screw (10). Lubricate its threads and the spherical socket. 4. Insert the two Phillips head screws that held the cover into the two pivot rods and, using the screws as handles, pull out the rods. 5. Lift out the handle.
1 Instructions for Use Loss of Sensitivity at High Leak Rates Loss of Sensitivity at High Leak Rates Repeated bakeouts at 450°C will result in partial annealing and a loss of tension in the spring washers that provide the force to open the valve. This will be evidenced by decreasing sensitivity of control at high leak rates. This is not a common situation, but may occur after months of use under high-temperature conditions. Replacement of the spring washers and adjustment are required. 26/36 1.
1 Instructions for Use Loss of Sensitivity at High Leak Rates Disposal Meaning of the "WEEE" logo found in labels The following symbol is applied in accordance with the EC WEEE (Waste Electrical and Electronic Equipment) Directive. This symbol (valid only in countries of the European Community) indicates that the product it applies to must NOT be disposed of together with ordinary domestic or industrial waste but must be sent to a differentiated waste collection system.
1 Instructions for Use Replacement Parts Replacement Parts Figure 5 Variable leak valve assembly drawing Please refer to the preceding figure Tab. 2 28/36 Ref. item Description Q.ty req.
1 Instructions for Use Replacement Parts Ref. item Description Q.ty req.d 12 Pivot rod 2 13 Pan head screw, 8-32 x 1/4 lg 2 14* Handle 1 15* Knob 2 16* Fine drive screw assembly 1 17* Fine drive spring washer 1 18* Collar 1 ---* Sapphire removal tool 1 ---* 5/16” Allen wrench 1 ---* 1/4” Allen wrench 1 ---* SST brush 1 ---* High temperature lubricant Fel-Pro C-100 1 Repair Kit Part Number SR0061417400 962-0014 * This item is part of Repair Kit 962-0014.
1 Instructions for Use Accessories Accessories Tab. 3 Description Part Number Mating ConFlat flange 2 ¾” -rotatable F0275-0150-RCE Mating ConFlat flange 2 ¾” –non-rotatable F0275-0150-NCE Copper gasket for 2 ¾” CFF – Pkg./10 FG-0275-CI Screw and nuts for 2 ¾” CFF – Pkg./25 FB-0275-CI Mating Mini-ConFlat flange 1 1/3” - rotatable F0133-0075-RCEW Mating Mini-ConFlat flange 1 1/3” – non-rotatable F0133-0075-NCE Copper gasket for 1 1/3” – pkg./10 FG-0133-CI Screw and nuts for 1 1/3” – pkg.
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