MV-112 Operation and Service Manual
Contents
1. OUTLET O RING BNC CONN SCREW CROSS REC FILL HD 6 32 x 1 4 SCREW CROSS REC FILL HD 4 40 x 7 8 SCREW CROSS REX FILL HD 4 40 x 3 16 SCREW CROSS REC PAN HD 2 56 x 1 8 SCREW CROSS REC ROUND HD 40 80 x 1 4 WASHER SPLIT LOCK 42 WASHER SPLIT LOCK 4 WASHER SPLIT LOCK 46 MAXTEK PART NO 112409 1 112408 112401 112402 112403 112404 803111 112202 112411 112421 803112 803197 888007 803097 803099 803100 803102 803101 803103 803107 803105 803161 800070 800071 800072 800073 800074 800122 800128 800129 USED ON MV 112 VALVE WITH VCR FITTINGS Maxtek Inc http www maxtekinc com 11980 Telegraph Road Santa Fe Springs CA 90670 6084 Tel 562 906 1515 e FAX 562 906 1622 Email sales maxtekinc com e support maxtekinc com REQ D COM ka Fa Fa WN CR L 85 WARRANTV Maxtek Inc guarantees the MV 112 Valve to be free of functional defects in material and workmanship and will perform in accordance to the specifications published bv Maxtek Inc in the appropriate brochure for a period of one 1 year from the date of original shipment to purchaser The foregoing warranty is subject to the condition that the valve be properly installed and operated in accordance with instructions provided by Maxtek Inc and has not been altered by anyone other than Maxtek Inc or has not been subject to abuse misuse accident or damage during shipment Purchaser s sole and exclusive remedy under the a2. level is increased the force generated at the peaks of the triangular waves becomes just sufficient to overcome the pre load and open the valve slightly for a very brief portion of each cycle As the D C level increases further both the amount and duration of opening in each cycle increase with increasing D C level If the valve was controlled at this level the control would in effect be a combination of amplitude modulation and duty cycle modulation Still further increases in D C level increase the amount and duration of valve opening in each cycle However the valve begins opening sufficiently far that further increases in the amount of opening do not significantly change the flow through the valve Control in this regime closely resembles pure duty cycle modulation Finally at sufficiently high D C levels the valve goes beyond its control range and is open all of the time as in duty cycle modulation with a 10046 duty cycle This drive method retains advantages of duty cycle modulation in that valve function is readily controlled and there is a self cleaning action which reduces the likelihood of valve clogging Because the dynamic voltage excursion is much less than in duty cycle modulation however the life of the piezoelectric crystal and the valve seat are extended In addition the small dynamic excursion leads to a quieter operation than with duty cycle modulation Experience with this method of control has also shown that stable co
3. 112800 REV F Maxtek Inc Model MV 112 Piezoelectric Gas Leak Valve Specifications VALVE TYPE PIEZOELECTRIC CRYSTAL CONTROLLABLE GASSES ANY COMPATIBLE WITH MATERIALS FLOW RANGE 0 500 SCCM CLOSED LEAK RATE 5 X 10 SCC SEC 1 ATM HE ON INLET RESPONSE TIME 2 MILLISEC MAXIMUM INLET PRESSURE 50 PSI DRIVE REQUIREMENT 0 100 VDC 10 LA or 0 24 VDC 15mA OPERATING TEMPERATURE RANGE 10 C TO 60 C MATERIALS STAINLESS STEEL VITON TEFLON NICKEL PLATED CRYSTAL INLET amp OUTLET CONNECTIONS 7 16 20 O RING PORTS PER SAE J514 14 SWAGELOK FITTINGS ARE STANDARD 14 VCR CAJON FITTINGS OPTIONAL ELECTRICAL CONNECTOR STANDARD BNC WEIGHT 800 GRAMS SWAGELOK IS A REGISTERED TRADEMARK OF THE SWAGELOK CO CAJON IS A REGISTERED TRADEMARK OF THE CAJON CO Maxtek Inc http www maxtekinc com 11980 Telegraph Road Santa Fe Springs CA 90670 6084 Tel 562 906 1515 e FAX 562 906 1622 Email sales maxtekinc com e support maxtekinc com DESCRIPTION HOUSING COVER HOUSING VALVE SEAT RETAINER CRVSTAL NUT SEAT ADJUSTMENT SPRING PRELOAD XTAL BALL PRELOAD CRYSTAL amp SEAL ASSEM FITTING INLET 14 SWAGELOK FITTING INLET OPTIONAL 4 VCR CAJON FITTING OUTLET O SWAGELOK TV FITTING OUTLET OPTIONAL 14 VCR CAJON CONNECTOR BNC FILTER ELEMENT SPRING FILTER SPRING VALVE SEAT O RING VALVE SEAT O RING CRYSTAL O RING COVER O RING FILTER O RING INLET amp
4. 3S IATA JNIH O LV3S ONIN O BER 43111 INJW4 13 ONINdS YSIS M3Q0N38 OIWVM320Z3ld ONIN O ONILLId 131100 ONILLIH L3 TNI JNISNOH SNIS O MANOS M3AOO ONIN O M3MOS 43NIVLIX M3MOS ONINdS QVOT3Md M3NIVI3M T1VISAMO ONIMdS QVOT3Md 43109 iv NO133 NMOHS LON ONG OL 3MIM Figure 2 Valve Construction 181 09 SLL AA ui WI NI SNOISN3NI0 14Od LIILNO 880 VIC vc NNOD ONG Vid SZ T L cm in Figure 3 Dimensions in 107 e f n 10 E Q 107 21 22 23 24 25 26 27 28 29 VOLTAGE Figure 4 Power versus Pressure 1 PRESSURE CONTROL INPUT SIGNAL ION GAUGE gt ION GAUGE CONTROLLER GAS SUPPLY TURE AUTOMATIC PRESSURE CONTROLLER OUTPUT SIGNAL 2 FLOW CONTROL GAS FLOW PROCESS SUPPLY TRANSDUCER CHAMBER INPUT SIGNAL DUTPUT 3 GAS COMPOSITION CONTROL RESIDUAL RESIDUAL GAS MV 112 GAS GAS SUPPLY TRANSDUCER ANALYZER INPUT SIGNAL OUTPUT SIGNAL VALVE CONTROLLER GENERALIZED CLOSED LOOP SYSTEMS Figure 5 Generalized Closed Loop Systems PUMPS INPUT VOLTAGE VDC Figure 6 Input Voltage vs Throughput 1000 900 800 700 600 500 THROUGHPUT IN STD cm min WITH 1 ATM PRESSURE DI
5. FFERENTIAL AT 25 C APPLICATION OF THE PIEZOELECTRIC VALVE MV 112 The MV 112 Piezoelectric Valve is suitable for applications requiring precision control of gas flow The following paragraphs outline the use of the valve in these applications including information relative to installation and calibration OPERATION GENERAL The valve is tested and calibrated at the factorv over an input voltage range of 0 100 VDC This range should not be exceeded in order to maintain factorv checked parameters The signal must be applied to the center of the standard BNC male connector while the ground is connected to the outer body Any 0 100 VDC power supply can be used for manual operation or an automatic pressure controller can be used for closed loop operation Compatible controllers are CONTROLLER VENDOR DGC III PERKIN ELMER QUADREX PPC INFICON 250 B SERIES OPEN LOOP OPERATION MANUAL For successful open loop control the parameter being controlled has to be visibly displayed so that the control voltage 0 100 VDC to the valve can be manually adjusted and the effects observed In addition the system must be slow responding to manually compensate for changes in related parameter CLOSED LOOP OPERATION The most common control system is of the closed loop type and is shown in general terms in Figure 5 The sensor used in the system and fed back to the valve determines the type of system i e a pressure sensor typifies a pressure control loop B
6. Valves have a response time of 1 to 10 seconds which is 500 to 5 000 times as long as the MV 112 and Mass Flow Controllers Valves have a 6 minimum flow rate of about 1 000 000 times higher than the MV 112 minimum rate INSTALLATION Installation of the MV 112 valve consists of plumbing the outlet port of the valve to a suitable port in the vacuum system The outlet port has a standard Swagelok 44 tube fitting for this purpose The gas supply Note Inlet pressure must be regulated to 50 PSI max is connected to the inlet fitting which is also a Swagelok 14 tube fitting which has been modified to retain the 7 micron inlet filter Gas flow direction is shown on the I D label on the valve housing OPERATION The electrical input to the valve is via a standard BNC female connector The control voltage is 0 100 VDC Polarity must be positive to center contact and negative to the housing Any 0 100 volt DC power supply can be used for manual operation or an automatic pressure controller such as Veeco s APC 100 can be used for closed loop operation ADJUSTMENTS Normally no adjustments are necessary The valve is adjusted at the factory for a threshold voltage voltage at which valve starts to open of 20 30 volts If this has decreased to the point where the valve is not leak tight it may be adjusted by removing warning label and turning the adjustment screw NOTE The adjustment screw is very sensitive Care must be used not to damage the crys
7. bove warranty is limited to at Maxtek s option repair or replacement of defective equipment or return to purchaser of the original purchase price Transportation charges must be prepaid and upon examination by Maxtek the equipment must be found not to comply with the above warranty In the event that Maxtek elects to refund the purchase price the equipment shall be the property of Maxtek This warranty is in lieu of all other warranties expressed or implied and constitutes fulfillment of all of Maxtek s liabilities to the purchaser Maxtek does not warrant that the product can be used for any particular purpose other than that covered by the applicable specifications Maxtek assumes no liability in any event for consequential damages for anticipated or lost profits incidental damage or loss of time or other losses incurred by the purchaser or third party in connection with products covered by this warranty or otherwise Repair and service beyond the warranty period will be provided by Maxtek Inc on a time and material basis at current Maxtek Inc prices INSTALLATION AND MAINTENANCE FEATURES A piezoelectric valve has several features that are advantageous over other valves They include no mechanical linkage no servomotor drives no wear no overshooting fail safe on loss of power with automatic close no leakage external adjustment minimum flow control and fast response less than two milliseconds For Example Mass Flow Controller
8. ectric valve has been modified and tested for pulsed operation and the data reported in industry journals MATERIALS The following is a list of materials used in the MV 112 compared to Veeco s PV 10 valve with properties of material reflected MAXTEK MV 112 PART MATERIAL 304 SS 304 SS 316 SS 316 SS 316 55 Viton 400 SS Viton 316 S8 Viton Teflon Teflon 400 SS 316 SS Viton Viton 304 S8 Ceramic Epoxy Nickel Viton 304 ES 400 SS 304 SS 316 SS Viton M Slightly Magnetic MM Very Magnetic V Poor High Vacuum Material Silver is Available VEECO PV 10 PART MATERIAL NOTES Bottom Body Cup Body Gasket Retainer Screw 2 Retainer Spring Preload Button Crystal Support Piezo Element Conductive Plating Bimorph Bonding Valve Seal Disk Wire Insulation Prelcad Spring Spring Seren G Locator Mastic Mal Boueing Best Fittings 2 Fitting O Ring 2 Feedthrough Connector Connector O Ring M Slightly Magnetic MM Very Magnetic V Poor High Vacuum Material Silver is Available Comparison of Piezoelectric Valve Materials COMPATIBILITY Gases such as Argon that are dry and non corrosive can be continuously exposed to the valve Gases such as Chlorine Ammonia and Hydrogen Sulfide will have a deleterious effect on the crystal and seal assembly in the valve The valve has been used with radioactive tritium gas with Viton seals replaced with EDPM MAGNETIC compatibility i
9. etween the sensor and the valve a controller is needed to compare the sensor input with a setpoint and generate an error signal The error signal is inverted and amplified to increase the voltage to the valve when the sensor is less than the setpoint and decrease the voltage to the valve when the sensor is more than the setpoint The setpoint is usually a controller adjustment The closed loop dynamic response is usually adjusted at the controller The valve response time of 2 milliseconds or less is much faster than the typical system response making system functionally insensitive to the valve response This should be compared to the 6 to 10 seconds associated with mass flow valves when picking your system configuration to assure a stable and accurate design As a system element the valve is fail safe in that it closed when power is removed has low inertia for minimum overshoot and no mechanical linkages for minimum wear and maximum reliability METHOD FOR DRIVING PIEZOELECTRICALLY ACTUATED VALVES Piezoelectrically actuated valves are employed for controlling small flows of gases A notable example is the piezoelectrically actuated inlet valve which is used for admitting gas to evacuated chambers at low controlled rates Such valves have been operated either by 1 a D C voltage fixed the level of which is adjusted to effect the desired opening or by 2 duty cycle modulation bang bang In duty cycle modulation the drive voltage is switc
10. hed between two extreme values at which two voltages the valve is fully closed and fully open respectively Varying the proportion of time at the two voltage levels effects control Both of these drive methods have shortcomings 1 With the D C operation a accurate control is difficult to achieve because of the hysteresis of the piezoelectric crystal and b when the valve opening is small a D C controlled valve is susceptible to clogging by contaminants 2 With duty cycle modulation accurate control is readily achieved and there is a self cleaning action which reduces the likelihood of clogging However valves which are driven by duty cycle modulation are often short lived because of the large frequent voltage and hence mechanical excursions which are required for operation when the valve is pre loaded to ensure sealing in the absence of an applied voltage A drive method for such valves having significant advantages is the saw tooth method where the voltage applied to the piezoelectric crystal is relatively small amplitude triangular wave which is superimposed upon an adjustable D C level Control is effected by adjustment of the D C level Operation of a piezoelectrically activated valve with this type of drive can be understood with reference to such a drive signal with gradually increasing D C level applied to a pre loaded valve While the D C level is low the force generated in the crystal remains closed At some point as the D C
11. ntrol is more easily achieved than with either duty cycle modulation or D C control PERFORMANCE PARAMETERS The performance parameters of the valve are few in number and easy to interpret The basic question is what flow can be obtained at a known pressure drop over the temperature extremes of the application The valve has been characterized over the temperature range of plus 10 C to plus 60 C and a flow range of 0 500 SCCM at 1 atm The valve will function at higher flow rates and temperature ranges and inquiries are welcome Figure lis data showing the effects of different threshold adjustments and temperature variations on performance These performance curves must be considered when matching the valve to the system gain controller drive range maximum throughput over temperature and control resolution Figure 4 provides data showing power applied versus pressure APPLICATIONS Typically the valve is used with a flow meter to control gas flow or an ion gauge to maintain a high vacuum or installed in multiple lines as an on off control in a gas mixing application The lift of applications includes but is not limited to the following Sputtering Sputter Etching Plasma Etching Ion Reactive Ion Milling Diffusion Furnaces Reactive Evaporation Pressure Calibration Svstems Reactive Sputtering Ion Beam Etching Tube Backfilling 10 Ion Profiler 11 Mass Spectrometer 12 Tokamak Fusion Reactor LO 10 U1 i amp N S A piezoel
12. s a function of the material used in the construction of the valve and the effect of the magnetic property on the valve performance The previous page lists the magnetically sensitive materials RELIABILITY Warranty returns have been 0 5 or less for all valves shipped to date The usual turn around time for returned valves is 48 hours If the crystal needs replacement the required burn in and seating procedures extends this to 10 days maximum
13. tal or valve seat NEVER turn adjusting screw more than 1 2 turn total Evidence of damage caused by improper adjustment or disassembly voids the warranty Turn screw in very small increments 1 degree or less at atime Turning the screw clockwise increases the threshold voltage Applying voltage to the valve until a pressure change is noted in the vacuum system or leak detector makes adjustment Note the voltage at which this occurs and turn screw clockwise to increase voltage required to open valve and counter clockwise to decrease voltage required MAINTENANCE Normally no maintenance is required If the filter becomes contaminated it is replaceable by removing the inlet fitting see valve construction drawing If further maintenance is required return the valve to the factory 1000 LIL 900 800 700 600 900 ATM PRESSURE ON INLET 400 500 WITH 200 100 THROUGHPUT IN STD cm min 1 pp US E O ed E A E ERE A EN US SS EA E ES O O 19 20 30 40 INPUT VOLTAGE VDC Figure 1 Temperature Effects on Throughput M3M2S INLSNFAV NOLLOQMISNOO 3AIVA ONISNOH INIWLSAFOV ONIMdS 1V
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