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Negative Pressure Instrument

By Jon Mcdonald,2014-11-25 18:58
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Negative Pressure Instrument

    Negative Pressure Instrument

    Operating and Maintenance Information

    For Models NP-2,NP-4 and NP-V

     Rev 11/04

    Contents………………………………

     Introduction ........................................................... 2

     General Description ............................................... 2

     Operation

     Startup ................................................................... 2

     Preheating.............................................................. 2

     Chamber Application ............................................. 3

     Vacuum Control .................................................... 3

     Maintenance

     Negative Pressure Chamber ................................... 4

     Chamber Cleaning ................................................. 4

     Orifice Plate Repair ............................................... 4

     Vacuum Leaks ...................................................... 4

     Temperature Control ............................................. 4

     Temperature Calibration ....................................... 5

     Electrical testing .................................................... 6

     Warranty and Service ............................................ 7

     Ordering Procedure ............................................... 8

     Technical data

     Orifice Plate Diagrams ......................................... 9

     Vacuum Problem Troubleshooting ...................... 10

     Electrical Power Drawing ..................................... 11

     Temperature Control Drawing.............................. 12

     Vacuum Distribution ............................................ 13

    Electronic Diversities

     986 Ridge Road Finksburg MD. 21048

     410. 876.1431 (voice/fax)

    WWW.ELECTDIV.COM

     1

INTRODUCTION

    The Negative Pressure Cutaneous Suction System was developed by Electronic Diversities as an experimental device to meet specific dermatological research needs.

    Over the years, suction blisters have been recognized as an important research tool for various dermatological and allergy studies. Researchers have resorted to various schemes to create suction blisters but our instrument provides a complete portable system that has successfully been used within the United States, as well as abroad, and found to be a simple, yet effective, method with high repeatability and reliability.

    Since the inception of the Negative Pressure Instrument System, there have been constant improvements and its use has expanded to accommodate the needs of researchers in several medical disciplines. This instrument represents one of the latest versions of the system, incorporating all changes and improvements to date. Currently, there are 3 models. The NP-2, a two heated chamber unit, the NP-4, a four chamber heated unit and the NP-V The NP-2 and

GENERAL DESCRIPTION

    The Negative Pressure Cutaneous Suction System is a self-contained instrument package that combines all the necessary elements to successfully create suction blisters on a patient's skin. The blisters are created through the use of suction chambers that are attached to the patient's skin. The instrument console contains the power source, vacuum pump, temperature controls and all related controls to operate multiple suction chambers. The suction chambers are connected to the console by a flexible connection. Each of the chambers is controlled by a preset temperature control to provide an optimal skin warming temperature. Both chambers share an adjustable common vacuum source that affects all chambers equally.

STARTUP

    Because each chamber is calibrated separately, it is important that the numbered

    chambers be connected to the proper chamber control channel. Failure to connect

    the chambers properly may result in chamber temperature calibration errors.

    Connect the blister chambers to the instrument observing the chamber numbering. Any number of chambers, up to the capacity of the instrument (2 or 4) can be used. The vacuum and electrical connections are simply plugged into the control console connections. Do not connect the vacuum connections of chambers that you do not intend to use. This will

    cause a large vacuum leak and adequate vacuum to the operating chambers will be impossible.

PREHEATING

    Preheating can be accomplished with the chambers either on or off the patient. It is a decision that can be made based on research criteria, patient comfort and researcher's desire. To start pre-heating, turn the POWER switch on. The power lamp should glow and the chamber lamps

    should come on. At this time the chambers are heating. The temperature of the chamber is preset typically to 40 degrees centigrade unless specified otherwise. As each chamber reaches it's preset temperature, the chamber lamps will cycle on and off. Typically, it takes 5 to 10 minutes for the chamber temperature to stabilize.

    Do not allow vacuum to be connected to a chamber that is preheating and not connected to a patient. The volume of airflow through the open chamber will cool the chamber faster than it can preheat!

     2

    If you connect the vacuum line to an unused chamber while other chambers are in use, a sudden drop of vacuum will experienced as chamber is evacuated by the system. This may damage any blisters already being formed.

     3

CHAMBER APPLICATION

    The chamber must be secured to the patient's skin by use of the hook and loop straps supplied. A leak proof fitting must be made between the skin and orifice plate or the vacuum will not form blisters. Once the process is started, the fit is usually not as critical as the vacuum tends to self-seal as the blisters are formed through the orifice openings.

    The chamber heating system, which provides a slight warming of the orifice plate and the patient's skin surface, enhances blister formation

VACUUM CONTROL

    Open the VACUUM control valve fully (CCW rotation) and turn on the VACUUM power switch. The VACUUM lamp should glow and the vacuum pump will run. At this time the vacuum gauge should read zero. Slowly close the vacuum control valve (CW rotation). The vacuum should start to increase as the connected chambers are evacuated. Adjust the vacuum bleeder valve for the vacuum desired. The gauge shows the vacuum for all chambers. The blister chambers cannot be adjusted individually.

    If the gauge does not show adequate vacuum there is a leak in either a chamber itself or the chamber/patient fit. Go to the vacuum troubleshooting chart for more information.

    The application of a moderate negative pressure from the instrument console, to the chamber interior, causes the patients skin to be gently drawn through the opening(s) in the orifice plate. The results are typical suction blisters, approximately the size of the opening(s) in the orifice plate. The skin and blister area is generally not damaged and patient discomfort is minimal.

    Time and vacuum values are strictly experimental and can best be achieved through trial and error. Excessive vacuum will cause rupture of the blister roof while inadequate vacuum will cause improperly formed blisters.

    MAINTENANCE

NEGATIVE PRESSURE CHAMBER

    The negative pressure chamber is fabricated of mostly plastic components, with two removable threaded caps. The upper cap is fitted with a clear viewing lens so that the actual blister formation can be observed. The opposite end of the chamber is fitted with a removable orifice plate that is placed on the patient's skin. Since this plate is simply threaded onto the chamber end, multiple plates with different opening patterns can be interchanged as desired.

CHAMBER CLEANING

    Do not use water or a steam autoclave to clean the chambers or connecting tubing. Damage to

    the electrical components will result.

    The plastic chambers should be cleaned only with alcohol swabs or wipes. The blister orifice plates, once removed from the chambers, can be cleaned in a like manner, washed, or steam autoclaved. After many autoclave cycles it is possible that the metal to plastic bond on the orifice plate will loosen. If this happens, the plates can be easily repaired by you (see orifice plate repair) or returned for service.

    If the chamber is disassembled for any reason pay particular attention to the positioning of the vacuum seals beneath the caps. Lubricate these seals with a small amount on lubricant such as K-Y jelly to assure a leak free seal.

     4

ORIFICE PLATE REPAIR

    If the metal orifice plate becomes loose in the orifice plate housing, the silicon seal has failed. The temperatures encountered in autoclaving and the dissimilar expansion and contraction of the metal plate and the surrounding plastic cap usually cause this. If you desire to repair the orifice plate, simply clean all traces of old silicon adhesive from the plate and collar. Thoroughly clean all parts with alcohol and allow to dry. Spread a small bead of silicon adhesive (General Electric-RTV or equal) around the groove of the orifice collar, Insert the orifice place and allow the silicon to exude from the joint. Wipe excesses with a cotton ball dampened with alcohol and allow to cure at least 12 hours. Optionally, The orifice plate and collar can be returned for factory service.

VACUUM LEAKS

    The vacuum system is a common manifold system, which means that all the chambers will se the same vacuum. The vacuum in the manifold is equalized to the atmospheric pressure by the vacuum adjustment Valve. With this design, a leak in any component will be reflected throughout the system.

    Vacuum leaks can be easily isolated since the vacuum gauge can be used to provide critical system information. Follow the vacuum troubleshooting chart for quick vacuum problem diagnosis.

TEMPERATURE CONTROL

    The blister chambers are controlled individually by a solid state control system. Since each chamber is separate, the chambers are calibrated at the time of production for each channel and are marked. If the chambers are improperly connected, a calibration error will result in the temperature of the chamber. When this unit was produced, the chambers were calibrated for an orifice plate temperature of ______degrees centigrade. Should another temperature be required the chambers can be adjusted by the user or returned for factory

     5

    Temperature Calibration

    Note: Generally, temperature calibration is unnecessary and it is not considered to be a user adjustment. By the nature of the instrument design, chamber and plate temperature fluctuations are normal and generally do not affect the success of the blister formation.

    CAUTION!

    HIGH VOLTAGE AND MOVING PARTS WILL BE PRESENT WHEN THE INSTRUMENT IS OPERATED WITHOUT THE OUTER CASE. ONLY PERSONS FAMILIAR WITH THE

    OPERATION OF ENERGIZED EQUIPMENT SHOULD PERFORM THIS PROCEDURE.

    TESTING SHOULD BE PERFORMED TO INSURE THE ELECTRICAL SAFETY

    OF THE UNIT AFTER REASSEMBLY

MATERIALS REQUIRED

     Small common blade screwdriver

     Accurate digital thermometer with a remote sensing element

     cotton balls

     Rubber bands

CALIBRATION PROCEDURE

    1.Remove the four screws in the corners of the front panel and the two screws on

    the bottom of the instrument

    2.Gently slide the instrument from it's housing. Take caution that the wire for the

    rear fan does not become damaged or detached

    3.Locate the chamber calibration controls on the bottom of the chassis. If the

     instrument is an NP-2 there is one circuit board. If the instrument is an NP-4

    there are two circuit boards. Each circuit board is divided into two sections.