BS ISO 6855-1:2012 pdf download – Mopeds — Measurement method for gaseous exhaust emissions and fuel consumption Part 1: General test requirements
7.2.8 A probe, located near to but outside the gas-collecting device, to collect, through a pump, a filter and a flowmeter, samples of the dilution air stream, at constant flow rates, throughout the test.
7.2.9 A sample probe, pointed upstream into the diluted exhaust mixture flow, upstream of the positive displacement pump or the critical flow venturi to collect, through a pump, a filter and a flowmeter, samples of the diluted exhaust mixture, at constant flow rates, throughout the test. The minimum sample flow rate in the two sampling devices described in 7.2.8 and 7.2.9 shall be 150 L/h.
7.2.10 Three way valves, on the sampling system, described in 7.2.8 and 7.2.9, to direct the samples either to their respective bags or to the outside throughout the test.
7.2.11 Gas-tight collection bags, for dilution air and diluted exhaust mixture of sufficient capacity so as not to impede normal sample flow and which will not change the nature of the gaseous exhaust emissions concerned. The bags shall have an automatic self-locking device, and shall be easily and tightly fastened either to the sampling system or the analysing system at the end of the test.
7.2.12 A revolution counter, to count the revolutions of the positive displacement pump throughout the test. Good care shall be taken with the connecting method and the material or configuration of the connecting parts because there is a possibility that each section (e.g. the adapter and the coupler) of the sampling system will become very hot. If the measurement cannot be performed normally due to heat-damages of the sampling system, an auxiliary cooling device may be used as long as the exhaust gases are not affected. NOTE 1 With open type devices, there is a risk of incomplete gas collection and gas leakage into the test room, so it is important to make sure that there is no leakage throughout the sampling period.
NOTE 2 If a constant CVS flow rate is used throughout the test cycle that includes low and high speeds all in one, it is advisable that special attention be paid because of higher risk of water condensation in high speed range.
7.3 Analytical equipment
7.3.1 The sample probe shall consist of a sampling tube leading into the collecting bags, or of a drainage tube. This sample probe shall be made of stainless steel or of some other material that will not adversely affect the composition of the gases to be analysed. The sample probe as well as the tube taking the gases to the analyser shall be at ambient temperature.
7.3.2 Analysers shall be of the following types:
a) non-dispersive type with absorption in the infrared for carbon monoxide and carbon dioxide;
b) flame ionization type for total hydrocarbons (diluted measurements);
c) non-dispersive type with absorption in the infrared for hydrocarbons (direct measurements);
d) chemiluminescence type for nitrogen oxides.
7.4 Cooling equipment
Throughout the test, a variable speed cooling blower shall be positioned in front of the moped, so as to direct the cooling air to the moped in a manner which simulates actual operating conditions. The blower speed shall be such that, within the operating range of 10 to 50 km/h, the linear velocity of the air at the blower outlet is within ± 5 km/h of the corresponding roller speed. At roller speeds of less than 10 km/h, air velocity may be zero.
As far as possible, the air speed shall be constant across the whole outlet section.
The blower outlet shall have a cross-section area of at least 0,2 m 2 and the bottom of the blower outlet shall be between 5 cm and 20 cm above floor level. The blower outlet shall be perpendicular to the longitudinal axis of the moped between 30 cm and 45 cm in front of its front wheel. The device used to measure the linear velocity of the air shall be located at between 0 cm and 20 cm from the air outlet.