Emission measurements of industrial valves according to TA Luft and EN ISO 15848-1 As the title suggests, in this article Professor Dr.-Ing Alexander Riedl looks into the implications of measuring emissions according to TA Luft and EN ISO 15848-1 and points out some important conclusions.
Professor Dr.-Ing. Alexander Riedl, University of Applied Sciences Muenster, Germany
TA Luft
Inasmuch as they relate to Germany,the “T echnische Anleitung zur Reinhaltung der Luft”(T echnical Guidelines for Air Pollution Control,or TA Luft for short and referred to hereinafter as TA Luft) [1] are like a law in character.Among other things,they pursue the objective of reducing emissions with gasket systems as normally ud in the chemicals and
petrochemical industries.TA Luft only
gives guidelines in respect of compliance
with permissible leakage limits and refers
to regulations which define basic
conditions for inspections.For shutoff
and regulating valves,this affects VDI
(Association of German Engineers)
Guideline 2440 [2],which may be
regarded as state-of-the-art from a legal
生态公园
perspective.
VDI 2440
Guideline VDI 2440 refers to average
gas-like emissions for differing gasket
systems but the are not upper limits
(e Table 1).
Table 1 – Average gaous emissions (leakage) and valve gaskets [1] Gasket system Leakage related to the average size
of the gasket [mg/(s x m)] Stuffing box with packing 1.0
Stuffing box with cup leather, O-ring0.1
Stuffing box with packing, stuffing box with cup leather,0.01
O-Ring (with "TA Air Certificate" according to
VDI 2440, Section 3.3.1.3)
太多英语Metallic bellows, aled0.01尽管近义词
Metallic bellows, aled (with flat gasket posssing0.001
a TA Luft Certificate according to VDI 2440)
Stuffing box with packing and aling medium/suction,No emission
metallic bellows, welded on both sides(technically leak-proof)
VDI 2440 refers to the u of high-
quality metallic bellows with a
downstream safety stuffing box or
equivalent gasket systems as a
朝花夕拾读后感50字
particularly effective means of reducing
emissions.In other words,metallic
bellows and so-called “equivalent gasket
systems”are established as conforming to
TA Luft.This means that only the kinds
of gasket systems may be ud in Germany on shutoff and regulating valves when a TA Luft medium is subsidid.
Gasket systems may be regarded as equivalent if they fulfil the following conditions:
(1) The construction of the gasket system转化思想
can be expected to permit its
regulation function under operating
conditions.
(2) Compliance with specific leakage rate
with reference to the average size of
the gasket,from 10-4mbar x l/(s x m)
at temperatures of less than 250°C
and from 10-2mbar x l/(s x m) at
temperatures on the gasket system of
greater than 250°C is proven at the
first inspection.
No specific explanation is given on construction under (1) as to why this guideline is difficult to understand.On the other hand,the determination of a leakage rate to be complied with under (2) for all gaskets except metallic bellows is crucial in order to get valves that fulfil the conditions of this certificate onto the market.
Guideline VDI 2440 describes a testing procedure with which the above-mentioned certificate can be shown.The ancillary conditions here are:(1) testing medium:helium;
娇绳媚雨(2) testing pressure:nominal pressure;
(3) testing temperature:permissible
operating temperature;
(4) before the test,a reprentative
number of switching cycles is carried
out depending on the operating
conditions (switching rate);
(5) test:with static and moving
spindle/shaft;
(6) leak rate:leakage resulting after at
least 24-hour admission flow with
helium under the given testing
conditions.
If the leak in (6) is less than 10-4mbar x
l/(s x m) (up to 250°C) or 10-2mbar x
l/(s x m) (over/the same as 250°C),the
valve may be regarded as TA Luft
compliant and may be ud with TA Luft
media.
EN ISO 15848-1
ISO norm EN ISO 15848-1 [3] has been
valid since 2006.It refers exclusively to
valves and describes,independent of the
guidelines of TA Luft and VDI 2440
白萝卜水的功效与作用respectively,detailed tests for
determining leakage and the creep
behaviour of valves.The norm was
developed under the overall control of
拿破仑滑铁卢
the CEN/TC 69 “Industrial Valves”
Committee.The norm distinguishes
between the following parameters:
(1) 3 grades of imperviousness for the
spindle/shaft;
(2) a grade of imperviousness for the
body gasket;
(3) 2 testing media (helium and methane);
(4) 3 grades of firmness;
(5) 5 grades of temperature;and
1 distinction between shutoff and
regulating valves.
Table 2 [3] shows the following grades of
imperviousness for die spindle and the
shaft:
Table 2 – Grade of imperviousness/leakage areas
Grade Measured leakage Remarks
rate mg/(s x m)
A Typically achieved with bellows gaskets or an equivalent (helium only)≤10-6spindle/shaft gasket system for swivel valves.
B≤10-4Typically achieved with packing on a PTFE basis
or elastomer packing.
C≤10-2Typically achieved with packing on the basis of
flexible graphite.
The required imperviousness for the body
gasket,measured using the sniffing method,
may not exceed 50 ppmv (1 ppmv = 1cm3
x /m3).In respect of the media,the norm
is not intended to achieve any
comparability,but less leakage may be
expected than with helium.However,this
statement requires testing.The leakage tests
are conducted both at room temperature
and at maximum operating temperature,
taking cycles of differing lengths.The gasket
connection may only be re-tightened to a
limited extent.
At the moment the author does not know
whether any European country or the EU
has adopted the norm in order to convert
the limits described here into national or
European law.Through the preci
guidelines,however,it is expected that this
will be carried out within the foreeable
future.The same applies to the stability and
temperature grades described below.
The shutoff and regulating valves differ by
stability grades,but the classification to a
grade of stability is given by the number of
cycles in which a certain grade of
imperviousness (e T able 1) has not been
exceeded.With the shutoff valves the norm
assumes a maximum cycle of 2500 and
with the regulating valves,a maximum
cycle of 105 cycles.Differences are
described in three grades of firmness
shown in T able 3 below.
H EADING
F UGITIVE E MISSION C ONTROL
Comparison of regulations
The guidelines in EN ISO 15848-1 are very preci and easy to understand.It is important to note here that clear guidelines are given in respect of the testing procedure.As well,the subdivision into grades of stability,imperviousness and temperature are significant in order to also enable the urs of valves to differentiate between them.The same applies to the subdivision into shutoff (low number of expected cycles) and regulating valves (high number of expected cycles).
The TA Luft and Guideline VDI 2440give a maximum permissible leakage as the only criterion which may not be exceeded;however,the marginal conditions (cycle etc.) are not clearly defined.In addition,the construction requirement which allows it to function according to the purpo for which it was built,is not really a clear guideline.But what is important is the question of the ufulness of EN ISO 15848-1 for verifying TA Luft.If we compare the degree of leakage in the ISO norm with the guidelines of TA Luft/VDI 2440,we arrive at the following interrelationship [4]:
T =temperature of the gas (K)X =leakage rate (mbar x l/s)Y =leakage rate (mg/m x s)Note:the dependence of the leakage on the temperature of the gas is not taken into account in EN ISO 15848-1.Accordingly,the conversion factor for leaks at room temperature,taking into account the relationship to the size of the spindle/shaft,is:
Y = 0,164 .X (2)
Y = leakage [mg/(s x m)]X = leakage [mbar x l/(s x m)]If one takes into account the fact that,according to TA Luft,the average size of the aling material for inspecting the leakage is the determining factor and that,by contrast,EN ISO 15848-1
includes the size of the spindle/shaft,we arrive at the following interrelationship:
Y dm = 0,164 D + d X d (3)
Y dm = leakage according to VDI 2440,in relation to the average size of the gasket [mg/(s x m)]
X d =leakage according to EN ISO
15848-1,in relation to the diameter of the spindle/shaft [mbar x l/(s x m)]
D =outside diameter of the aling
element (corresponds to the
interior diameter of the body) [mm]D =exterior diameter of the
spindle/shaft [mm].
In most cas this probably means that,on achieving grade B imperviousness according to EN ISO 15848-1,the guidelines of TA Luft are probably also fulfilled.The same applies to
imperviousness grade C at temperatures of over 250°C.
Esntially,it may be assumed that EN ISO 15848-1 constitutes a tightening of the criteria in contrast to TA
Luft/VDI2440,as more temperature cycles can be carried out with the ISO-Norm.Table 3 – Stability grade for shutoff and regulating valves
Type
Stability grade
Cycle Temperature cycles
C015002Regulating valve
C021,5003C032,5004CC120,0002Regulating valve
CC260,0003CC3
100,000
4
Table 4 – Grade of temperature
Grade of temperature (t-196°C)(t-46°C)(tRT)(t 200°C)(t 400°C)Temperature
-196°C
-46°C
Atmospheric 200°C
400°C
temperature
The testing temperatures are subdivided into five grades and an area of -29°C x 40°C is given for room temperature (e Table 4).
M • f Y =
R
•
T
•
π•D
X (1)
where:
D =average gasket diameter (m)
f =conversion factor (=100) (m
g x Pa
x m 3/g x mbar x l)M =molecular mass (g/mol)R =general gas constant (8,314)
(J/mol x K)
2d Literature
[1] TA Luft:T echnical Guidelines for Air Pollution Control (TA Luft).Heymanns Verlag,Cologne,2002.[2]VDI 2440:Reducing Emissions from Mineral Oil Refineries.Beuth Verlag,Berlin,2000.
[3] DIN EN ISO 15848-1:Industrial Valves - Measuring,T esting and Qualification Procedures for Escaping Emissions - Part 1:A Classification System and
Qualification Procedures for the T esting the Design of Valves.Beuth Verlag,Berlin,2006.
[4] D.Bathen,C.Hummelt,J.
Meil:Emissions on Flanged Joints.Vulkan Verlag,Esn,2000.
