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```					                                       API Standard 674
Positive Displacement Pumps - Reciprocating

Standard           Edition                     Section              Inquiry #                    Question                                          Reply
674     Second Edition, June 1995             2.3                            With reference to the Second Edition of       The metric formula for calculating the power
API 674, please check the correctness of      required for driving a single-acting power
the mathematical formula for calculation      pump (Section 2.3.7) and the power required
of pump power in clauses 2.3.7 and 2.3.8.     for driving a double-acting power pump
(Section 2.3.8) are incorrect as shown in API
Standard 674, Second Edition, June 1995. In
both cases, the lead term should be divided
by 36, as you correctly stated in your letter.

674      Second Edition, June 1995         Sec. 1.5.2            674-I-02/99 Amongst the standards listed is API 676.       The nozzle loads given in API 676 are not
Are the nozzle loads given in API 676          applicable to pumps designed per API 674.
applicable to API 674?                         The only reference within API 674 to API 676
is in Paragraph 1.1 SCOPE to indicate which
standard applies to each type of pump.
There is no paragraph in API 674 addressing
nozzle loads (forces and moments). These
will be covered in the next revision of API
674.
674      Second Edition, June 1995   1.5, 3.1.11, 3.2.2, 3.5.3   674-I-01/00 Is it true, that by listing API 677, API 671   No torsional analysis is mandated by API
and API 613 as reference publication           Standard 674.
within API 674, the necessity to perform a
torsional analysis is automatically
implemented in any project to be handled
according to API 674 ?

674      Second Edition, June 1995          3.6.2.2.1            674-I-01/01 I have a question concerning API 674           The peak-to-peak value is from the minimum
chapter 3.6.2.2.1 and the interpretation of    to the maximum, not from the mean to either
the formula (eq. 3-1) which describes the      the minimum or maximum.
maximum allowable pulsation. The
maximum pulsation in this equation is
defined as the peak-to-peak value. Does
the ptp value mean from the minimum to
the maximum value of the pulsation or
describe the equation for the amplitude
which means from the mean value of the
pulsation either to the minimum or
maximum value?

674      Second Edition, June 1995              2                674-I-02/01 Does the three years of uninterrupted          Yes. Paragraph 2.1.1 calls for at least three
operation include or intend to cover oil       years of uninterrupted operation. Any
changes?                                       lubrication system should meet this
requirement, or the vendor must note an
exception to the standard.
674      Second Edition, June 1995          3.6.2.2.1            674-I-03/01 Regarding API 674 chapter 3.6.2.2.1 and        The allowable peak-to-peak pulsation level
the interpretation of the formula (eq. 3-1)    described in Equation 3-1 refers to the value
which describes the maximum allowable          from the minimum to the maximum of one
pulsation. The maximum pulsation in this       pulsation cycle.
equation is defined as the peak-to-peak
value. Does the p-t-p value mean from the
minimum to the maximum value of the
pulsation or the amplitude, that is, from
the mean value of the pulsation either to
the minimum or maximum value?
API Standard 674 - Positive Displacement Pump

Standard     Edition     Section      Inquiry #
674      2nd - June      2.1       674-I-02/01
1995

674      2nd - June      2.3
1995

674      2nd - June      1.5.2     674-I-02/99
1995

674      2nd - June   1.5, 3.1.11, 674-I-01/00
1995         3.2.2, 3.5.3

674      2nd - June    3.6.2.2.1   674-I-01/01
1995

674      2nd - June    3.6.2.2.1   674-I-03/01
1995

674      2nd - June   Appendix A 674-I-01/04
1995
API Standard 674 - Positive Displacement Pumps - Reciprocating

Question
Does the three years of uninterrupted operation include or intend to
cover oil changes?

With reference to the Second Edition of API 674, please check the
correctness of the mathematical formula for calculation of pump power
in clauses 2.3.7 and 2.3.8.

Amongst the standards listed is API 676. Are the nozzle loads given in
API 676 applicable to API 674?

Is it true, that by listing API 677, API 671 and API 613 as reference
publication within API 674, the necessity to perform a torsional analysis
is automatically implemented in any project to be handled according to
API 674 ?
I have a question concerning API 674 chapter 3.6.2.2.1 and the
interpretation of the formula (eq. 3-1) which describes the maximum
allowable pulsation. The maximum pulsation in this equation is defined
as the peak-to-peak value. Does the ptp value mean from the minimum
to the maximum value of the pulsation or describe the equation for the
amplitude which means from the mean value of the pulsation either to
the minimum or maximum value?

Regarding API 674 chapter 3.6.2.2.1 and the interpretation of the
formula (eq. 3-1) which describes the maximum allowable pulsation.
The maximum pulsation in this equation is defined as the peak-to-peak
value. Does the p-t-p value mean from the minimum to the maximum
value of the pulsation or the amplitude, that is, from the mean value of
the pulsation either to the minimum or maximum value?

Background: In the “Operating Conditions” section of the API 674
datasheet (lines 16 and 17), we have a maximum discharge pressure of
100 kPa and a minimum which is not specified by the purchaser.

Question 1: Is it correct to consider the indicated pressure value as the
operating pressure?

Question 2: Is it correct to test the pumping unit only at the operating
pressure point indicated?
umps - Reciprocating
Last update: November 9, 2006
Yes. Paragraph 2.1.1 calls for at least three years of uninterrupted
operation. Any lubrication system should meet this requirement, or
the vendor must note an exception to the standard.

The metric formula for calculating the power required for driving a
single-acting power pump (Section 2.3.7) and the power required
for driving a double-acting power pump (Section 2.3.8) are
incorrect as shown in API Standard 674, Second Edition, June
1995. In both cases, the lead term should be divided by 36, as you
The nozzle loads given in API 676 are not applicable to pumps
designed per API 674. The only reference within API 674 to API
676 is in Paragraph 1.1 SCOPE to indicate which standard applies
to each type of pump. There is no paragraph in API 674
covered in the next revision of API 674.
No torsional analysis is mandated by API Standard 674.

The peak-to-peak value is from the minimum to the maximum, not
from the mean to either the minimum or maximum.

The allowable peak-to-peak pulsation level described in Equation 3-
1 refers to the value from the minimum to the maximum of one
pulsation cycle.

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