PVA MV250-LL Operation Manual Download Page 5

 

Theory of Operation 

 
The MV250-LL is a rod displacement style metering valve designed to dispense small volumes of fluid 
with the highest degree of accuracy. This true positive displacement valve will dispense one small dot of 
fluid with each full cycle. Fluid volume is determined by the micrometer adjustment setting and cannot be 
affected by changes in fluid viscosity due to temperature or changes in fluid delivery pressure. 

MV250-LL volumetric fluid displacement range: 

 

 

(0.0001 cc – 0.012 cc)       

The MV250-LL has a divorced design comprising of two major sections.  These include: 

 

Air section (red anodized portion) 

 

Fluid section (stainless steel portion) 

Air Section 

The air section is an aluminum body with a simple piston/cylinder combination used to cycle the valve. A 
micrometer adjustment in the upper air body controls how far the piston and needle assembly can retract 
thus altering the volume of fluid that can be metered and dispensed during each cycle. 

Fluid Section 

The fluid section is a stainless steel body, which includes a needle, seat, and two integral check valves to 
make up the metering chamber. The metering chamber fills as the needle retracts away from the seat, then 
dispenses as the needle moves back toward the seat. Such fluids may include but are not limited to; 
solvents, epoxies, UV adhesives, silicones, RTV, grease, etc.    

 

Wetted parts on the MV250-LL include: 

 

303, 304 stainless steel 

 

Teflon

®

 

 

Kalrez

®

 

 

Safety 

 
Due to material contents being under pressure eye protection is required for operators. Refer to MSDS 
sheets on material being dispensed for other precautions. 

 

Setup

 

 
The MV250-LL requires a 2-position, 4-way air solenoid valve to actuate the air section. The valve should 
be operated with clean, dry air between 60-100psi. Two #10-32 threaded air ports are located on the air 
section of the valve. The port located closest to the mid-section of the valve is air actuating to fill the fluid 
chamber. The port located furthest from the mid-section of the valve is air actuating to dispense material. 
Quick connect air fittings are typically supplied with the MV250-LL to fit 5/32"od tubing. Note that the 
valve should be normally in the filled and ready to dispense position. 

Fluid is supplied to the MV250-LL through the 1/8"npt port located on the stainless steel fluid section of 
the valve.  

Summary of Contents for MV250-LL

Page 1: ...i MV250 LL POSITIVE DISPLACEMENT VALVE Version 112 5825 Operation Manual Revision A Date March 2014 ...

Page 2: ...nges subsequently made Precision Valve Automation Inc makes no representation or warranty expressed implied or statutory with respect to and assumes no responsibility for the accuracy completeness sufficiency or usefulness of the information contained herein No warranties of merchantability or fitness for purpose shall apply This document including the information contained herein is the property ...

Page 3: ...stions or problems arise do not hesitate to contact PVA s Valve Service Department for support This department can be reached at PVA headquarters via telephone or e mail Again thank you for your purchase and we look forward to assisting you in the future as you continue to improve your dispensing processes PVA Contact Information Main Office Technical Support Sales Support PVA Six Corporate Drive ...

Page 4: ...ing and Disassembly 8 Assembly Instructions 10 General 10 Air Section 10 Fluid Section 10 Assemble Sections 11 Setting Micrometer to Zero 11 Micrometer Adjustment Breakdown 12 Spare Parts 13 Bill of Materials for MV250 LL 166 Troubleshooting 177 PVA Warranty Policy 188 Table of Figures Figure 1 Solenoid Valve 6 Figure 2 Tool Kit Contents 6 Figure 3 Micrometer Adjustment Breakdown 12 Figure 4 Micro...

Page 5: ...wo integral check valves to make up the metering chamber The metering chamber fills as the needle retracts away from the seat then dispenses as the needle moves back toward the seat Such fluids may include but are not limited to solvents epoxies UV adhesives silicones RTV grease etc Wetted parts on the MV250 LL include 303 304 stainless steel Teflon Kalrez Safety Due to material contents being und...

Page 6: ... Kit Contents Qty Part Number Description 2 0266244 8 Adjustable Wrench 2 26563 3 32 Hex Key 1 26561 5 64 Hex Key 1 26559 1 16 Allen Key 1 5516A18 Tweezers 1 B62 0752 Mineral Oil Lubrication Kit 2 5cc 1 B62 2048 Silicone Lubricant for O ring 2 5cc 1 9570K71 Hook and Pick Set 1 0266255 Pliers 2 53085A61 Soft Plastic Covers for Pliers 1 PB135 2 Screw Driver for Micrometer 1 PT17184 Micrometer Adjust...

Page 7: ... section 7 and tighten with an adjustable wrench Pressurize the material to be dispensed between 10 20 psi To bleed the fluid section use a 3 32 Hex key to loosen the set screw 17 of the bleed port located on the fluid section 7 being careful not to fully remove the screw Note If fluid does not flow out of the bleed port slowly increase material pressure until fluid and air bubbles are seen or wig...

Page 8: ... may require occasional tightening as wear occurs in order to prevent leaks around the packing Routine Cleaning and Disassembly Cleaning and rebuilding the valve will be required from time to time A spare parts kit part MV250 LL SP is available with all the normal wear parts included Begin disassembly by removing air and fluid pressure from the valve Remove all pneumatic tubing and fluid delivery ...

Page 9: ...e the upper air body 2 from the lower air body 20 to remove the spring 9 then slide the end cap 19 off of the needle 1 Holding the lower air body 20 in one hand grab the needle 1 then push the needle and piston 21 assembly out of the lower air body Remove the 004 Buna O ring 23 from the lower air body 20 Hold the piston 21 with an adjustable wrench then use a 5 64 Hex key to unthread and remove th...

Page 10: ...w 16 using an adjustable wrench and 5 64 Hex key to tighten Mount the other 014 Buna O ring 28 onto the piston 21 Apply a small amount of silicone grease to the inside of the lower air body 20 then drop in the piston and needle assembly Mount the 004 Buna O ring 23 on the end of the needle 1 and slide it down into the groove in the end of the lower air body 20 Slide the end cap 19 onto the needle ...

Page 11: ...ip of a 3 32 Hex key tighten the packing nut 3 Setting Micrometer to Zero When assembling the valve it will be necessary to re calibrate the micrometer adjust back to the zero position Using the wrench A insert the inside tip of the small end into the orifice of the midsection D and rotate it clockwise until the numbered centerline is on a side that can most easily be viewed by the operator Note V...

Page 12: ...justment Breakdown Figure 3 Micrometer Adjustment Breakdown Reference Letter Section Description A Micrometer Wrench B Top Screw C Dial D Micrometer Midsection E Collar F Micrometer End Figure 4 Micrometer Section Key ...

Page 13: ...or this valve product number MV25 LL SP includes the following components Figure 5 Spare Parts Kit Contents Qty Part Number Description 1 114 4750 Needle 1 214 3441 Packing Teflon 1 214 6507 Seat 1 V125 Washer 1 VLV 004B 004 Buna O ring 1 VLV 004K 004 Kalrez O ring 1 VLV 006K 006 Kalrez O ring 1 VLV 007B 007 Buna O ring 1 VLV 007K 007 Kalrez O ring 2 VLV 014B 014 Buna O ring Figure 6 Drawing 112 5...

Page 14: ...s considered confidential and proprietary information It is delivered on the express condition that it not be used disclosed or reproduced in whole or in part for any reason without prior written consent of PRECISION VALVE AUTOMATION Inc DESIGN DATE DRN BY REVISION DESCRIPTION REV RJB 09OCT12 RJB ORIGINAL DESIGN A JA 12 19 14 DER REMOVED SIDE PLUG B C D E F UNLESS OTHERWISE SPECIFIED DIMENSIONS AR...

Page 15: ...302 SS 2 114 6556 UPPER AIR BODY 1 6061 ALUM 3 114 9206 PACKING NUT 1 303 SS 4 214 3441 PACKING 1 VIRGIN PTFE 5 214 6176 CHECK VALVE BODY INLET 1 303 SS 6 214 6177 CHECK VALVE BODY OUTLET 1 303 SS 7 214 6180 FLUID BODY 1 303 SS 8 214 6507 SEAT MV250 1 303 SS 9 01344 SPRING 1 SS 10 01423 MICROMETER HEAD 1 11 01469 SETSCREW 5 40 x 3 16 1 18 8 SS 12 02367 CHECK VALVE 1 SS 13 02368 CHECK VALVE 1 SS 14...

Page 16: ... Lower Air Body 1 10 VLV 014B 014 Buna O ring 2 11 V202 Piston 1 12 114 4595 Upper Air Body 1 13 VLV 007B 007 Buna O ring 2 14 SH5 40x2 0 Socket Head Cap Screw 2 15 SH5 40x2 25 Socket Head Cap Screw 2 16 VLV 006K 006 Kalrez O ring 1 17 VLV 004B 004 Buna O ring 1 18 01344 Spring 1 19 V001 Set Screw 1 20 V300 Luer Adapter 1 21 V125 Washer 1 22 01423 Micrometer Adjustment 1 23 V007 Bleeder Plug 1 24 ...

Page 17: ...sen set screw on fluid body to bleed air Valve leaks from mid section Packing nut is loose Packing is worn Tighten packing nut until snug Replace packing Valve does not dispense anything Air trapped in fluid body needle adapter or dispense needle Valve is not cycling Fluid pressure is too low Material cured in fluid section Micrometer adjustment set too low Flip valve upside down and cycle until a...

Page 18: ...ties extend only to the original purchaser Third party warranty claims will not be honored at any time Prior to returning a product for a warranty claim a return authorization must be obtained from PVA s customer service department Authorization will be issued either via the telephone facsimile or in writing upon your request To qualify as a valid warranty claim the defective product must be retur...

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