Hong Kong Regulations

AIR POLLUTION CONTROL (PETROL FILLING STATIONS) (VAPOUR RECOVERY) REGULATION - SCHEDULE 1

STATIC PRESSURE PERFORMANCE TEST FOR THE VAPOUR RECOVERY SYSTEM OF A REGULATED VEHICLE

(Past version on 01/04/1999).

[section 8A] (L.N. 218 of 2004)

1. General

This procedure applies to the determination of the five-minute static pressure
performance of a vapour recovery system of a regulated vehicle by fluid
mechanical principles.

2. Determination of compliance

2.1 The outlet of any vent pipe serving the vapour recovery system shall be
fitted with a pressure/vacuum valve. 2.2 For tests in sections 5.1 and 5.2,
the following requirements shall be complied with the maximum allowable
pressure change in 5 minutes for the petrol delivery tank of a
regulated vehicle shall be as tabulated below which has been-

   (a)  pressurized to 4.48 kPa (457 mm water column, gauge); or

   (b)  evacuated to -1.49 kPa (152 mm water column, gauge vacuum). Capacity
        of a petrol delivery tank or a compartment

   (litres) Allowable pressure change in
5 minutes per petrol delivery
tank or compartment tested
(kPa (mm water column, gauge)) 9475 or more 0.127 (13) 5685 to 9474 0.186 (19)
3790 to 5684 0.245 (25) 3789 or less 0.314 (32)

2.3 For tests in section 5.3, the maximum allowable pressure change in the
vapour return line in 5 minutes (difference between initial and final
pressures) shall be 1.25 kPa (127 mm water column, gauge).

3. Principle and summary of test procedure

The regulated vehicle is to be tested in a location where it will be protected
from direct sunlight. The petrol delivery tank on the regulated  vehicle is to
be pressurized, isolated from the pressure source, and the pressure drop
recorded to determine the rate of pressure change. A vacuum test is to be
conducted in the same manner.

4. Test equipment

4.1 Source of air or inert gas capable of pressurizing tanks to 6.9 kPa

(704 mm water column, gauge). 4.2 Low pressure (1.25 kPa (127 mm water column,
gauge) divisions) regulator for controlling pressurization of tank. 4.3 Water
manometer with 0 to 6.22 kPa (0 to 635 mm water column, gauge) range, with
scale reading of 0.01 kPa (1 mm water column, gauge). 4.4 Test cap for vapour
line with a shut-off valve for connection to the pressure and vacuum supply
hoses. The test cap is to be equipped with a tap for connecting the manometer.
4.5 Caps for liquid delivery line. 4.6 Vacuum pump of sufficient capacity to
evacuate tank to -2.49 kPa (254 mm water column, gauge vacuum). 4.7 Pressure
and vacuum supply hose of 6.4 mm internal diameter. 4.8 In-line,
pressure-vacuum relief valve set and checked to activate at 6.9 kPa (704 mm
water column, gauge) and -2.49 kPa (254 mm water column, gauge vacuum) and
with a capacity equal to the pressurizing or evacuating pumps.

5. Test procedure

5.1 Static pressure performance, positive pressurization

5.1.1 Static pressure performance measurement

   (a)  Check all the pressure/vacuum valves serving the petrol delivery tanks
        to ensure that they are working properly.

   (b)  Open and close the dome covers.

   (c)  Connect static electrical ground connections to tank. Attach the
        delivery and vapour hoses, remove the delivery elbows and plug the
        liquid delivery fittings.

   (d)  Attach the test cap to the vapour recovery line of the regulated 
        vehicle.

   (e)  Connect the pressure and vacuum supply hose and the pressure-vacuum
        relief valve to the shut-off valve. Attach the pressure source to the
        hose. Attach a manometer to the pressure tap.

   (f)  Connect compartments of the petrol delivery tank internally to each
        other if possible.

   (g)  Apply air pressure slowly, pressurize the tank, or alternatively the
        first compartment, to 4.48 kPa (457 mm water column, gauge).

   (h)  Close the shut-off valve, allow the pressure in the petrol delivery 
        tank to stabilize (adjust the pressure if necessary to maintain 4.48
        kPa

(457 mm water column, gauge)), record the time and initial pressure.

   (i)  At the end of 5 minutes, record the final time and pressure. 5.1.2
        Pressure change from 4.48 kPa (457 mm water column, gauge)

   (a)  Calculate the pressure change from 4.48 kPa (457 mm water column,
        gauge) to the final pressure, and compare the pressure change to the
        requirements in section 2.2.

   (b)  Repeat for each compartment if they were not interconnected.

5.2 Static pressure performance, negative pressurization

This procedure does not apply unless pressurized air lines or other equipment
penetrate the petrol delivery tank headspace. 5.2.1 Static pressure
performance measurement

   (a)  Check all the pressure/vacuum valves serving the petrol delivery tanks
        to ensure that they are working properly.

   (b)  Connect vacuum source to the pressure and vacuum supply hose.

   (c)  Slowly evacuate the petrol delivery tank, or alternatively the first
        compartment, to -1.49 kPa (152 mm water column, gauge vacuum). Close
        the shut-off valve, allow the pressure in the petrol delivery tank to
        stabilize (adjust the pressure if necessary to maintain -1.49 kPa (152
        mm water column, gauge vacuum)), record the time and initial pressure.
        At the end of 5 minutes, record the final time and pressure. 5.2.2
        Pressure change from -1.49 kPa (152 mm water column, gauge vacuum)
        Calculate the pressure change from -1.49 kPa (152 mm water column,
        gauge vacuum) to the final pressure, and compare the pressure change
        to the requirements in section 2.2.

5.3 Internal vapour valve performance, positive pressurization

5.3.1 Static pressure performance measurement

   (a)  After completing the pressure and vacuum tests, pressurize the petrol 
        delivery tank as in section 5.1 to 4.48 kPa (457 mm water column,
        gauge).

   (b)  Close the petrol delivery tank's internal valve(s) including the
        internal vapour valve(s), thereby isolating the vapour return line and
        manifold from the petrol delivery tank.

   (c)  Relieve the pressure in the vapour return line to atmospheric
        pressure.

   (d)  Seal the vapour return line and after 5 minutes record the gauge
        pressure existing in the vapour return line and manifold. 5.3.2
        Pressure change from 4.48 kPa (457 mm water column, gauge) Calculate
        the pressure change from 4.48 kPa (457 mm water column, gauge) to the
        final pressure, and compare the pressure change to requirements in
        section 2.3.