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Thread: ref question

  1. #1
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    ref question



    hi every one
    my question is
    if i want to press air conditioner 2 ton split unit type type with air to detect leaks
    which valve i should choose discharge or suction valve
    i know i must use discharge but some people say that i should use suction valve
    why i dont know
    there prove is some split unit came with valve on suction line only



  2. #2
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    Re: ref question

    if the system has two conection for gauges then use them both to make sure you get pressure all round the system

  3. #3
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    Re: ref question

    as you know if i want to press the system i should lock up one of them
    so as example if i pressed system from discharge valve
    then suction valve should be closed
    can you explain more

  4. #4
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    Re: ref question

    warning!-do not pressure test with air!- use oxygen free nitrogen, and pressure test on both gauge points if possible- if theres only 1 on the low side-use it,
    also do not shut any valves!
    Quote Originally Posted by kefah View Post
    hi every one
    my question is
    if i want to press air conditioner 2 ton split unit type type with air to detect leaks
    which valve i should choose discharge or suction valve
    i know i must use discharge but some people say that i should use suction valve
    why i dont know
    there prove is some split unit came with valve on suction line only

  5. #5
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    Re: ref question

    oh my god
    in iraq we pressure a c unit with air to detect leaks
    i mean shutting valves
    if i want to pressure test on outdoor unit i shut one of the valves and pressure the other
    Last edited by kefah; 17-05-2012 at 09:38 PM.

  6. #6
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    Re: ref question

    www.ior.org.uk page 1 of 2 December 2007
    SERVICE ENGINEERS’ SECTION GOOD PRACTICE GUIDE 24
    Pressurising installed systems
    with nitrogen to find leaks
    This Good Practice guide is intended to cover
    the identification of leaks using Nitrogen for
    refrigeration systems which are already in
    operation and are known to have undergone a
    strength pressure test. This leak tightness
    testing procedure will sometimes be necessary
    to comply with the standard leakage checking
    requirements of the F-Gas regulations.
    The majority of leaks can be found by either
    visual examination or use of either an electronic
    leak detector or a proprietary bubble solution.
    Where the leak cannot be identified or the gas
    charge has been lost, then it will be necessary
    to find the leak by pressurising the system with
    Nitrogen.
    To carry out this procedure safely it is
    important to use the correct equipment, carry
    out a risk assessment and then follow the test
    procedure.
    The test pressure
    The maximum test pressure to be used should
    be the maximum allowable pressure, which
    should be stated on the equipment label. On
    smaller systems the suction and discharge
    pressures will be the same, however on larger
    equipment the maximum allowable suction
    pressure will be lower and the system will need
    to be tested in several sections.
    If the system information is not available a
    general guide to pressures which could be
    encountered are:
    Refrigerant Suction
    pressure
    Discharge pressure
    R134a 7.1bar 13.7bar
    R407C 13.2bar 23.6bar
    R404A 14.1bar 24.8bar
    R410A 18.8bar 33bar
    These have been established assuming a
    maximum condensing temperature of 55°C and
    a maximum ambient temperature of 32°C (as
    specified in EN378 – Refrigerating systems and
    heat pumps – Safety and environmental
    requirements).
    Using the correct equipment
    The nitrogen must be oxygen free (OFN) or
    High Purity. Oxygen must
    never be used as it
    can explode when mixed with oil, causing
    serious damage to equipment and injury or
    death to those in the vicinity.
    It is essential to use a suitable regulator with
    the nitrogen cylinder. The regulator has an
    output limiting device to prevent over
    pressurising of systems. The rating of this must
    be higher than the test pressure to be used but
    not excessively so.
    Maximum likely pressures:
    Refrigerant Maximum
    Pressure
    Suitable
    regulator
    R134a 13.7bar maximum
    output of 26bar
    R407C 23.6bar maximum
    output of 33bar
    R404A 24.8bar maximum
    output of 33bar
    R410A 33bar maximum
    output of 40bar
    There are now specific Nitrogen Pressure test
    kits on the market which use braded steel
    hoses. These are safer to use than a standard
    manifold and should be considered.
    Warning - use of Manifolds with sight glasses
    This guide assumes the use of Refrigerant Manifold
    and Gauges. It is essential that the manifold
    does
    not
    have a sight glass. These sight glasses have been
    known to fail and risk causing serious injury to the
    engineer carrying out the test. The manifold, gauges
    and service lines must be in good condition.
    Manifolds with sight glasses are only suitable for
    refrigerant recovery.
    www.ior.org.uk page 2 of 2 December 2007
    It is essential that appropriate personal protection
    equipment (PPE) is used when carrying out this
    test and this should include: safety goggles, gloves
    and a hard hat as well as normal work wear,
    including safety footwear.
    The Risk Assessment
    Before any work can take place it is mandatory to
    carry out a risk assessment. For guidance on
    carrying out risk assessments and sample generic
    versions for Nitrogen Pressure Leak Testing see
    the British Refrigeration Association Guidance.
    This assessment can then be put into practice
    taking into account the particular site conditions.
    It is essential that this takes into account the
    safety of personnel carrying out the test as well as
    other personnel on site not involved in the
    operation.
    Handling of nitrogen cylinders
    When the cylinder is not being used ensure the
    valve is closed. Never transport or store the
    cylinder with the regulator fitted.
    Dangers of Use of Nitrogen
    You will be pressure testing at high pressures
    with nitrogen. The pressures are high enough to
    cause serious injury or death. Nitrogen is an
    asphyxiant – it will suffocate you in high
    concentrations. The following guidelines show
    how to minimise risk during pressure testing.
    Pressure testing procedure
    If there is any residual refrigerant left in the
    system this must be recovered prior to following
    this procedure.
    1.
    Ensure the nitrogen cylinder is either secured
    or located in a position so that it cannot fall over.
    2. Ensure the regulator valve is wound
    fully out (counter clockwise / anti clockwise).
    3. Fit the regulator to the cylinder.
    4. Fit gauges to the system and ensure there are
    no isolated sections within the part of the system
    to be pressure tested.
    5. Fit the common manifold hose to the nitrogen
    cylinder.
    6. Open the system valves and open the high side
    manifold valve (to avoid damaging the low side
    manifold gauge do not pressurise the low side of
    the manifold with the test pressure).
    7. Open the nitrogen cylinder valve.
    8. Slowly wind the nitrogen regulator in
    (clockwise) to pressurise the system:

    Pressurise the system in stages of no more than
    3 bar (45 psi) at a time;

    Ensure you only pressurise the relevant sections
    of the system to their maximum allowable
    pressure.

    Listen for audible pressure loss at every
    pressure increment increase;
    • Watch the gauge for pressure loss.
    • If a leak is identified, the nitrogen should be
    vented, the leak repaired and the leak test
    procedure repeated.
    9. When the maximum system allowable pressure
    has been reached, close the nitrogen cylinder
    valve and the high pressure manifold valve.
    10. Note the pressure shown on the high
    pressure gauge.
    11. Wind the nitrogen regulator valve fully out
    (counter clockwise / anti clockwise).
    12. Carefully remove the common hose from the
    regulator, slowly venting the nitrogen pressure.
    13. Maintain the system at the maximum allowable
    pressure for the duration of the test.
    14. Test each joint with leak detection spray or
    soapy water to identify the leak point. If leaks are
    found, they
    must not be repaired with the
    system pressurised.
    15. Slowly vent the remaining nitrogen.
    16. Repair any leaks found and then repeat the
    test procedure using OFN.
    17. When it is established that the system is safe
    and leak tight the OFN can be evacuated and the
    system can be recharged with refrigerant.
    For more information

    HSE GN4 Safety In Pressure Testing ISBN
    0717616290

    BS EN 378 (2007) - Refrigerating systems and
    heat pumps – Safety and environmental

    Regulation pursuant to Regulation (EC) No
    842/2006 of the European Parliament and of
    the Council, on standard leakage checking
    requirements for stationary refrigeration, air
    conditioning and heat pump equipment
    containing certain fluorinated greenhouse
    gases

    British Refrigeration Association’s Risk and
    Task Assessments.

    Material Safety Data Sheets for nitrogen.
    The information contained in this Guide should be seen as a guide to interpretation of relevant industry standards, legislation and statutory information
    which should be consulted by the relevant competent person responsible for servicing refrigeration equipment. The Service Engineers’ Section and the
    Institute of Refrigeration accept no liability for any errors or omissions.
    Service Engineers’ Section of the Institute of Refrigeration, Kelvin House, 76 Mill Lane, Carshalton SM5 2JR

  7. #7
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    Re: ref question

    thank you pal

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