Welch Vacuum 1376N User Manual

WELCH-IL

OWNER’S MANUAL FOR

CHEMSTAR® VACUUM PUMP MODELS:

1400N

Never block the Exhaust Port.

If the exhaust port is blocked, pressure will build-up in the pump with

the potential of the pump body bursting and causing possible injury to

Welch-Ilmvac 5621 W. Howard Street Niles, IL 60714 Phone: (847) 676-8800 (Technical Support) Fax: (847) 677-8606 E-Mail: gdwelchvacuum@gardnerdenver.com Web-Page: www.welchvacuum.com

WARNING

personnel in the area.

Part No. 67-0544 R3.6

Printed in USA

INSTRUCTION

WARNING AND CAUTION

PLEASE READ BEFORE OPERATION

While reading your manual, please pay close attention to areas labeled:

WARNING AND CAUTION.

The description of each is found below.

WARNING

Warnings are given where failure to observe instruction could result in

injury or death to people.

CAUTION

Cautions are found where failure to observe the instruction could result

in damage to the equipment, associated equipment and process.

These units conform to the SI International system of units of measurement.

The following symbols (with recommendation of IEC1010 ) of warning will be found on the pump.

Caution - Refer to accompanying documents

Caution - Risk of electrical shock

Caution - Hot surface

WARNING

Motor includes a self resetting thermal cutout and the pump could restart

without actuation under fault condition.

TABLE OF CONTENTS

Section Page Section 01 - Installation

1.10 Introduction 4 Section 02 - Operation

2.10 Starting Procedures 6

2.20 Operation and System Optimization 7

2.21 High Pressure Operation 7

2.22 Gas Ballast Principles and Usage 7

2.23 System Leaks - Impact and Detection 8

2.30 Shutdown Procedure 8 Section 03 - Maintenance

3.10 Vacuum Problems 9

3.20 Oil Changes and Oil Level 9

3.30 Shaft Seal Replacement 10

3.40 Repairing Oil Leaks 11

3.50 Repairing Vacuum Leaks 11

3.60 Drive Problems 11 Section 04 - Trouble Shooting Guide

4.10 Poor Vacuum Readings 12

4.20 Noisy Pump 12

4.30 Excessive Oil Mist 12 Section 05 - Quick Reference Chart Chart 13 Section 06 - Dimensional Drawings (with rotation) Vacuum Pump 14 Section 07 - Pumping Speed Curves Speed Curves 15 Section 08 - Exploded Views and Parts Lists Vacuum Pump 16 Section 09 - Accessory Section Chart 17 Section 10 - MSDS - Sheets for DIRECTORR® OIL MSDS-Sheet for 1407K 19 Section 11 - Application Booklet Using your Chemstar 22

Section 1: INSTALLATION

1.10 Introduction This manual has been complied not only for the care and maintenance of the CHEMSTAR pump now in your

possession but as a helpful reference and guide for many problems which are usually associated with mechanical vacuum pumps. Take time to read these instructions carefully and preserve this manual for future reference; we think it will be useful to you.

1.11 Unpacking Carefully remove the pump from the shipping case and unfasten and remove the wooden skid. Preserve all

paper work and inspection tags for future reference. If damage has occurred from shipment a claim must be ﬁ led with the carrier immediately; preserve the shipping container for inspection by the carrier. If you are required to communicate with your dealer or with Welch Vacuum be sure to include your order numbers for quick identiﬁ cation. Do not return the pump to the factory without ﬁ rst completing the on-line request form for returned goods authorization at www.welchvacuum.com.

1.12 Pump Mounting

1.121 Mounted Pumps Rubber bumpers are supplied with most of our mounted pumps, either loosely or attached. Bumpers are

excellent for applications involving a semi-ﬂ exible surface such as a bench top; they help to isolate noise and eliminate creeping. For more rigid requirements, the pump base may be bolted directly to a ﬁ rm foundation with or without the bumpers. All CHEMSTAR pumps should be mounted in a horizontal plane.

1.122 Unmounted Pumps If you have purchased an unmounted pump, refer to parts list for information concerning the motor, motor pulley

and belt necessary to drive your particular pump at the recommended speed.

1.13 Pump Location The pump should be located preferably in a clean and well ventilated area and adequate space should

be provided wherever possible for routine maintenance such as changes of oil and belt adjustments and replacements. Above all, the pump should be located as closely as possible to its system in order to utilize it most efﬁ ciently. Its location should include such determining factors as the length and size of connections, the number of bends and the type of exhaust connections.

1.14 Exhaust Provisions (See Accessory section in back of this manual.) Exhaust connections will be determined by the type of system to be exhausted and the desired cleanliness of

the atmosphere surrounding the pump. Under normal conditions of mild evacuation nothing more than the dust cap will be necessary to cover the port. Where relatively high gas ﬂ ows are involved or where the presence of oil vapor is objectionable an exhaust ﬁ lter may be fastened to the exhaust port in place of the dust cap. The exhaust ﬁ lters used on our pumps are capable of absorbing and restricting any vapor particle larger than 0.1 micron.

WARNING

Never block the Exhaust Port. If the exhaust port is blocked, pressure

will build-up in the pump with the potential of the pump body bursting

Where extreme exhaust conditions are encountered it is best to pipe the exhaust direct out of the building. Welch

recommended wire reinforced PVC, metal pipe or thick walled rubber hose be used as exhaust lines to avoid potential of line becoming crimped or collapsing resulting in the exhaust port being clocked. Be sure to call Welch technical service prior to start-up at 847-676-8800 if you have any questions.

and causing possible injury to personnel in the area.

1.15 Electrical Power

1.151 Power Source Review Review the power source and the motor rating to be sure they agree in voltage, phase and frequency. On three-

phase applications the direction of rotation of the motor must be considered. Make a momentary check rotation at the time of power installation and wiring. Momentary backward rotation of the pump is not harmful. Check the layout drawings for proper direction of rotation.

CAUTION

Make certain the power settings on the pump match your power source

before attempting to operate the pump

1.152 Overload Protection Motor thermal overload protection is made available by the motor manufacturer as an aid to minimizing motor

failure. Overload protection is a standard feature on all single-phase 60Hz motors. Single-phase motors will normally have automatic overload protection. Motors of 1-1/2 horsepower or larger supplied with CHEMSTAR pumps contain no overload protection. Installations of such equipment must comply with local electrical codes which dictate appropriate starter and protection devices. It is strongly suggested that you familiarize yourself with the protection supplied with your motor so that you may react accordingly in the event of an emergency. Automatic reset protection is designed to reset itself after a predetermined cooling period. If the fault to the drive remains unaltered, the motor will cycle on and off until the fault is corrected. The motor data plate will indicate the presence of thermal protection.

1.16 Vacuum Connections (See Accessory Section in back of this manual.)

1.161 Choice of Connections The choice of connections and ﬁ tting can have a very marked effect on the pumping speed at the vacuum

chamber. Any connection placed between the pump and the chamber creates an impedance to the ﬂ ow of gas. This is particularly true at low pressures in the millitorr range where the gas ﬂ ow is substantially molecular in character. The gas ﬂ ow is then dependent upon the kinetic activity of the molecules to bring it to the intake of the pump.

1.162 The Effects of Conductance It has been shown that the conductance of a tube is proportional to the cube of its radius and inversely

proportional to its length. Therefore it is imperative that the connecting lines be as large in diameter and as short in length as practical. For best results the diameter of the connecting tube should be at least as large as the diameter of the pump intake. To avoid a large reduction in pumping speed at the vacuum chamber, it is clear that the conductance of the line must be considerably greater than the speed of the pump.

1.163 Metal Joints If metal piping or tubing is used, it is preferable to solder or braze all of the connections. Where threaded joints

must be used, coat the threads with LocTite® Thread Sealant with PTFE, or Leak Lock and screw together tightly. Flanged connections with elastomer gaskets make excellent demountable joints. Modular vacuum piping and ﬁ ttings are now extensively used.

1.164 Rubber Tubing Joints Where metal tubing is used between the system and the pump intake, joints can be make by butting the ends of

the two sections together in a short section of vacuum hose. Worm-screw band clamps are useful for securing the hose to the tubing. Whatever the joint you choose to use, cleanliness should be of utmost importance.

1.165 Valves and Stopcocks Metal valves or stopcocks may be used in the connecting line between the system and the pump to provide a

means of isolating the pump from the system. To minimize the impedance of ﬂ ow, the valve openings should be as large as possible. Lubricate the rotating plug of the stopcock with a ﬁ lm of vacuum grease sufﬁ ciently thick enough to prevent seizure.

1.17 Traps (See Accessory section in the back of this manual.)

1.171 The need for a Trap Where corrosive vapors or large quantities of condensable vapors are evolved from vacuum processing, a cold

trap may be used in the connecting line to the pump. It will help prevent damage to the pump mechanism and reduce oil contamination. The cold trap, immersed in a suitable Dewar ﬂ ask, is installed to that the vapors may come in contact with the surfaces of the trap and condense. Commonly used refrigerants are liquid nitrogen or dry ice and acetone. The refrigerant to be used depends upon the freezing point of the contaminations. A variety of cold traps are available from Welch-Ilmvac.

1.172 The care of a Trap When using a cold trap the refrigerant should be maintained at a high level in the ﬂ ask to keep the trap at a

uniformly low temperature. If the trap is re-warmed it may allow re-evaporation of the condensate. The refrigerant add tube on the liquid nitrogen trap should not be obstructed as the refrigerant boil-off can produce dangerously high pressures. If the trap becomes saturated it should be disconnected from the system, drained and cleaned. An increase in pressure in the vacuum system will normally indicate that the trap has become saturated. To clean the trap, remove the trap from the system, allow the trap to warm up and rinse off the condensate with a suitable solvent in a fume hood. Thoroughly clean and dry the trap before reinstalling in the system.

Section 2: OPERATION

2.10 Starting Procedures

2.101 Starting a CHEMSTAR Pump Before attaching the pump to a system it is well to familiarize yourself with the function and action of the pump

which you have now required. Remove the intake and exhaust port plugs and temporarily provide a stopper for the intake and a dust cap for the exhaust. Review the power requirements as described in Section 1.4.

CAUTION

Do not run this pump with the intake open directly to the atmosphere.

The pump will overheat, excessive oil mist will be emitted from the

2.103 Cleanliness Take every precaution to prevent foreign from entering the pump. A ﬁ ne mesh screen is provided for this purpose

in the intake passage of all CHEMSTAR pumps.

2.104 Oil Level Determination The amount of oil suitable for efﬁ cient and satisfactory performance should be determined after the pump has

reached its operating temperature. Initially, however, the pump should be ﬁ lled with fresh oil while the pump is idle. Fill the pump until the oil level falls half way of the oil level window. If after a short period of operation the level should fall, it is likely the result of oil entering some of the interior pockets of the pump. If the oil level rises, this signiﬁ es oil has drained into the pump cavity while pump was idle. Shut off pump, then drain oil down to proper level.

If a gurgling sound occurs, additional oil must be added. Mechanical pumps will gurgle in varying degrees under

four conditions of performance: [a] when operating at high pressure as in the beginning cycles of evacuation of a chamber; [b] when the oil level in the pump reservoir is lower than required; [c] when a large leak is present in the system; and [d] when the gas ballast is open. Awareness of the possibilities will save time in setting up a system. Best performance of a mechanical pump is generally obtained after sufﬁ cient time has been allowed for the pump to come to operating temperature.

exhaust and the pump will eventually seize.

2.20 Operation and System Optimization

2.21 High Pressure Operation CHEMSTAR two-stage pumps are designed to be most efﬁ cient when operated at or near their ultimate blanked

off pressure. The pump is designed to remove air from a vacuum system at atmospheric pressure to a deep vacuum. When the pump is operated at elevated pressures up to about 10 Torr for long periods of time, the pump will run hotter. At elevated ambient temperatures under these conditions, the thermal protection switch on single phase motors may cut out. Use of an exhaust ﬁ lter with coalescing element is required.

CAUTION

Do not run this pump for prolonged periods of time at or above 10 Torr. The pump

will overheat, excessive oil mist will be emitted from the exhaust and the pump will

Leaky vacuum systems, too large a vacuum chamber for pump size or high gas loads to the vacuum systems are

causes for extended runs of the pump at elevated pressure. If you need additional information, please contact Welch Vacuum at 847-676-8800, extension 1, for further information and precautions.

2.22 Principle of Gas Ballast

2.221 Effects of Unwanted Vapor Systems which contain undesirable vapors cause difﬁ culty both from the standpoint of attaining desirable ultimate

pressures as well as contamination of the lubricating medium. A vapor is deﬁ ned as the gaseous form of any substance which is usually a liquid or a solid. Water, oil and a mercury vapors are three of the more common vapors encountered in typical vacuum systems. When such vapors exist in a system, the vapors or mixtures of gas and vapor are subject to condensation within the pump; the precipitated liquid may thus ultimately dissolve or become emulsiﬁ ed with the lubricating medium. This emulsion is recirculated to the chambers of the pump where it is again volatilized causing increased pressure within the system.

2.222 Presence and Removal of Condensate Condensation takes place particularly in the compression stroke of the backing or second stage of a two-stage

pump. The compression stroke is that portion of the cycle during which the gas drawn from the intake port is compresses to the pressure necessary to expel it past the exhaust valve. Condensation takes place when the ratio between the initial pressure and the end pressure of the compression is high, that is, when the mixture of vapor and gas drawn from the intake port is compressed from a low pressure to high pressure. By adding air though the gas ballast valve to the mixture of vapor and gas being compressed, the pressure required for delivery past the exhaust valve is reached with a considerably smaller reduction of the volume of the mixture; this, depending upon the amount of air added, condensation of the vapor is wither entirely avoided or substantial reduced.

2.223 Pump Function With Gas Ballast In a pump functioning on a contaminated system and operating without the gas ballast, compression within

the stage takes place in the normal manner until the saturation pressure of the contaminating vapor contained within the mixture of gas and vapor is reached. The saturation pressure of water vapor is that pressure and corresponding temperature at which the dew point of the vapor is reached and condensation occurs. The saturation pressure of water vapor at an ambient temperature of 20°C is 17.5 Torr, while at 60°C, the approximate operating temperature of a pump, the saturation pressure is 149 Torr. The external side of the exhaust valve is subjected to atmospheric pressure. Consequently a compressive force somewhat greater than atmospheric pressure is required to open the valve and permit expulsion of the gas. Sometime during increased compression of the mixture of gas and vapors, the saturation pressure of 149 Torr for the water vapor is reached and the vapor condenses. The condensate is then allowed to emulsify with the oil which is recirculated within the pump stages this providing continued contamination of the system.

2.224 Pump Function With Gas Ballast On the other hand, when ballast air at atmospheric pressure is supplied to the compression stroke by means of

the gas ballast, the partial pressure of the unwanted vapor becomes a very small part of the total pressure of the mixture of gas, vapor and newly supplied air. The vapor is thus prevented from reaching its saturation pressure corresponding to the temperature of the pump and is ﬁ nally expelled form the pump as a vapor.

2.225 Controlled Ballast Flow Some degree of variation in ballast ﬂ ow may be obtained by the amount of opening applied tot he gas ballast.

Two or more turns of the gas ballast are sufﬁ cient to open it wide. With the gas ballast open, the sound of the exhaust is similar to that of a pump operating against a large leak. Because of the increased pressure introduced into the compression stroke, the pump must work a little hard to function, thus resulting in an increased operating temperature of approximately 8°C over a prolonged period of time. Tests have shown that continuous and prolonged operation for several weeks under these conditions is not injurious to the pump.

eventually seize.

2.226 Other Forms of contamination control The application of the gas ballast is a moderate and very successful method for the removal of

condensable vapors. For very heavily laden systems, other means of removal such as oil separators may be required. For mild cases of contamination the simple expedient of a cold trap or a change of oil serve the purpose.

2.23 System Leaks - Impact & Detection

2.231 Large Leaks The importance of eliminating all leaks in a vacuum system is obvious when it is realized that a leak

into the system, at atmospheric pressure, expands in volume by a factor of 750,000 to 10,000,000 or more. The pump must remove this added volume to maintain the desired vacuum. Fortunately a number of effective techniques for leak detection have been developed. Large leaks can be located by pressurizing the system and painting the suspected area with a thick soap solution. Escaping air will produce soap bubbles.

2.232 Small Leaks Small leaks may also be detected by spraying a suspected area with acetone or gases rich in

hydrogen, and observing a sudden change in pressure on an electrical gauge. The difference in calibration of these gauges, for air and other gases, will produce a distinct change in the pressure reading. To use this method of detection, the system must be under vacuum and the gauge sensing tube must be located between the pump and the area to be probed. Use extreme caution, as these materials are highly ﬂ ammable!

2.233 Fine Leaks Locating very ﬁ ne leaks requires a helium-sensitive, mass-spectrometer leak detector. This instrument

will locate leaks which cannot be detected by any other method. Numerous ﬁ ne leaks can have the total effect of a large leak.

2.30 Shutdown Procedures

2.301 A few simple precautions are all that is necessary when shutdown is in order. If a gauge is connected

CHEMSTAR Shutdown

to the system, ﬁ rst isolate the gauge, then turn off the power and open the system to atmosphere. If the pump is removed from the system, cover the intake port with a rubber stopper or suitable cover to protect the pump against contamination and loose particles. If the pump has been contaminated in service and is going to be shelved for a prolonged period it is best to drain the oil and reﬁ ll with a fresh charge.

Section 3: MAINTENANCE

3.10 Vacuum Problems

3.101 Pressure Determinations Leakage, contamination and unusual outgassing are the general causes of problems associated with

poor vacuum. To operate at maximum efﬁ ciency a system must be thoroughly clean. If the system is completely clean and free from leaks, and unwarranted vacuum problems still exist, the pump should be checked. A simple criterion for the condition of a mechanical pump is a determination of its ultimate pressure capability. This can be accomplished by attaching a gauge directly to the pump. The gauge may be any suitable type provided consideration if given to the limitations of the gauge being used. Refer to Paragraph 1-8 for further suggestions. If the pressure is unusually high, the pump may be badly contaminated, low on oil or malfunctioning. On the other hand, if the pressure is only slightly higher than the guaranteed pressure of the pump, an oil change may be all that is required.

3.102 Oil Contamination The most common cause of a loss in efﬁ ciency in a mechanical pump is contamination of oil. It is

caused by condensation of vapors and by foreign particles. The undesirable condensate emulsiﬁ es with the oil which is recirculated and subject to re-evaporation during the normal cycle of pump activity thus reducing the ultimate vacuum attainable. Some foreign particles and vapors may form a sludge with the oil, impair sealing and lubrication and cause eventual seizure. A gas ballast calve is helpful in removing vapors, especially water, but it is not equally effective on all foreign substances; therefore, periodic oil changes are necessary to maintain efﬁ cient operation of the system. The required frequency of changes will vary with the particular system,. Experiences with the process will help you determine the normal period of operation before an oil change is required.

3.103 Oil Overheating This pump is designed to operate continuously below 10 Torr. Continuous operation of this pump

above 10 Torr will lead to overheating and eventual pump failure. See Section 2.21, High Pressure Operation.

WARNING

Solvents, such as acetone, used to clean different pumps are extremely

hazardous. Inhalation may be fatal or harmful. Acetone is also

extremely ﬂ ammable. Never use acetone near heat or open ﬂ ame. Use

3.20 Oil Changes and Oil Level

3.201 Developing a Maintenance Schedule After studying many examples of pump failure, Welch has found the most common reason is poor

condition of the oil. This is why a regular maintenance schedule for the oil is critical to obtain the longest service life out of your of the oil on a daily basis in the early days of a new process or experiment. You want to look for discoloration of the oil and whether the oil level is rising. The discoloration can indicate deterioration of the oil and a rising oil level can indicate condensation of vapors is occurring in the pump. When changes occur, the oil needs to be change. If no changes in the oil level or color are observed, extended pump service life is obtained if the oil is changed every three to four months.

3.202 Forced Oil Flushing When you drain oil through the drain valve, you are not removing the oil and contaminants that are

inside the pumping mechanism. You are removing oil only from the oil case. Welch recommends a forced oil ﬂ ush of CHEMSTAR pumps be performed at the regular maintenance oil change. The procedure for the forced oil ﬂ ush is given below.

CHEMSTAR pump. Welch recommends that you examine the condition

only in a well ventilated area.

3.203 Forced Oil Flushing Procedure

1. Check the oil level, if the oil level is well above the ﬁ ll mark (This may indicate either the pump has been overﬁ lled with oil or has ingested a liquid or a large amount of vapor water or organic solvents). Please go to step

2. If the oil level is even with the ﬁ ll mark and you do NOT suspect corrosive gases or particulates (hence forth called contaminants) ingested have damaged the mechanism, run the pump for 15 minutes to allow the pump oil to warm up before going to step 2.

2. Turn off motor for the vacuum pump. Drain the oil into a clear plastic container (may need pliers to open drain valve). Look for contaminations settling to the bottom of container. If you see contaminants, you will need to repeat step 3 through 5 several times until the oil comes out clear. The oil you drained from the pump came from the oil case only. There may be contaminants in the pumping mechanism. To be sure all contaminants have been removed, the pump mechanism needs to be ﬂ ushed.

3. Make sure the belt guard is installed before proceeding further. Attach a short hose to the drain valve which runs into a clear plastic container.

4. Flushing the pump is carried out by adding a cup of CHEMSTAR vacuum pump oil through the intake port (IN) while the pump is turned on for 15 to 20 seconds. While adding the pump oil, the palm of your hand is placed lightly over the exhaust port (OUT). Look for water coming out of the drain. Turn off the pump.

5. Repeat step 4 until clean oil comes out of the drain hose.

6. Close the drain valve and ﬁ ll the pump with the amount of CHEMSTAR vacuum pump oil your pump needs.

7. Plug the intake (IN) port with a rubber stopper. Turn the pump on and run the pump for 10 minutes. Close the gas ballast.

8. Check the vacuum reading of the pump by connecting a thermocouple gauge tube to the pump’s intake. If the pump is running nearly as good as when it was new, the total pressure reading you will read on wither of these two gauges will be at least 10 micron.

A simple way to connect the gauge tube to the pump is to run the threaded tip of tube through a hole in a rubber

stopper. Use pump oil as a lubricant for inserting the tube. The stopper chosen should be bigger than the outer diameter of the intake ﬂ ange.

3.204 Reﬁ lling The Pump

After you are satisﬁ ed that the pump has been thoroughly ﬂ ushed, reﬁ ll the pump by pouring new CHEMSTAR

oil into the exhaust port. Fill to the indicated level and start the pump with the intake closed. A gurgling noise is characteristic when high pressure air is drawn through the pump. It should disappear quickly as the pressure within the pump is reduced. If gurgling continues, add sufﬁ cient additional oil through the exhaust port until gurgling ceases.

3.30 Shaft Seal Replacement

To replace the shaft seal of a pump, drain the oil and remove the pump pulley and key. Remove the screws

securing the old seal and pry it loose with a screwdriver or similar wedge, being careful not to mar the surface of the pump body against which the seal ﬁ ts. Discard the seal and its gasket, inspect all surfaces and repair any damages with a ﬁ ne abrasive stone. Wipe all sealing areas clean and place a ﬁ lm of CHEMSTAR oil on both the shaft and the inside bore of the new shaft seal. Using a new gasket, carefully slide the new seal into position and center it on the shaft. It is not necessary to apply any sealant to the gasket. Tighten the mounting screws uniformly and reﬁ ll the pump with CHEMSTAR oil. Follow instructions included in repair kit.

3.40 Repairing Oil Leaks

3.41 Location, Cause and Effect

Oil leaks may develop wherever two mating faces are sealed with a gasket. Such seams may fail as the result of

deterioration of the gasket material, loosening of the screws caused by temperature variations, or improper care as the result of previous reassembly. Typical gaskets seams in a mechanical pump are located at the oil level window, the shaft seal, the oil drain, and the mating faces of such mechanical surfaces as the intake chamber cover, the oil case, and the exhaust chamber cover. The importance of a gasket seam is determined principally by its function. If it is a vacuum seal, the ultimate performance of the pump is dependent upon it. If it is an oil seal, the pump may be operated satisfactorily for some time without loss of function. Eventually, of course, a great loss of oil may cause harmful damage.

3.402 Repairing Techniques

An oil seam may be sealed by any of several methods. When an O-ring is employed, the surfaces of the O-ring

and its groove should be wiped clean. If the O-ring is not badly deformed or scratched it may be reused by sealing with a slight ﬁ lm of vacuum oil or vacuum grease. Thin composition gaskets are generally used for large irregularly shaped areas. A replacement joint of this type should be thoroughly cleaned of all previous gasket material and the mating surfaces cleaned of any nicks.

3.50 Repairing Vacuum Leaks

3.501 Surface Preparation

Good Vacuum seals are an essential and important attribute of a good mechanical pump. A good seal is

dependent upon the quality of the mating surfaces as well as the sealant and its preparation. The mating faces should be carefully inspected for any projections or foreign particles which might interfere with proper mating. Slight projections such as nicks and burrs are most easily removed by rubbing with a ﬁ ne abrasive stone. The surface of the mating parts may be washed with a solvent or alcohol after which they must be thoroughly dried.

3.502 Temporary Repair

Temporary vacuum repairs are often made by covering the known leak with an industrial sealant such as Loctite

with PTFE. Such a practice, however, is not recommended for seals of a permanent nature.

3.60 Drive Problems

If for any reason the pump will not operate, turn off the power and check the fuse and electrical connections.

Then try the power to the motor only by removing the belt. If the motor operates properly try hand-rotating the pump in the proper direction with the pump intake port open. If both turn freely then replace the belt and check the belt tension. The tension should be sufﬁ cient to drive the pump without visible slippage. Any greater tension will cause noise and possible damage to the bearings of both the motor and pump. Make certain that both pulley grooves are clean and free from oil. The pulleys must be fastened securely on their respective shafts, and in parallel alignment.

+ 23 hidden pages