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CDOIF
Chemical and Downstream Oil
Industries Forum
CDOIF is a collaborative venture formed to agree strategic areas for
joint industry / trade union / regulator action aimed at delivering
health, safety and environmental improvements with cross-sector
benefits.
Guideline – Demonstrating Prior Use v4
Page 26 of 30
Where:
N
MH
=
Q
RT
Q
R
i j
k
l
m
+ nkkop + j
Q
RR
Q
R
i nkkop
t
CE
– Channel equivalent mean down time (hour)
(this is the combined down time for all the components in the channel of the sub-system).
N
MH
=
Q
RT
Q
R
i j
k
l
m
+ nkkop + j
Q
RR
Q
R
i nkkop
t
qr
=
$.+ s $#
tu
vrw xyzw
0.{0 s $#
tu
vrw xyzw
x j
a{"# xyzw| +
+ 7 hoursp + j
~." s $#
tu
vrw xyzw
0.{0 s $#
tu
vrw xyzw
x 7 hoursp
t
qr
= (0.253 x 4387) + ( 0.76 x 7 hours)
t
qr
= (1110) + ( 5.3 hours)
t
qr
= 1115 hours
bIR
Fcd
= [(Q
RT
) + (Q
RR
)] N
MH
PFD
= [1.2 x 10
{
per hour + 3.6 x 10
{
per hour ]x 1115hours
bIR
Fcd
= . i l
As with the result of any calculation, a sanity and sensitivity check should be conducted to ensure
that the results are realistic. It is often a practise to provide a statistical analysis of uncertainties.