Q&A Report Short Course 39 (Both Sessions).xlsm

	A	B	C	D
1	Question Report Short Course 39 First Session
2	Report Generated:	2/27/25 3:20
3	Topic	Webinar ID	Actual Start Time	# Question
4	Session No 39 (Eastern): An Introduction to Positive Displacement Pumps	837 8984 2657	2/27/25 1:45	22
5	Question Details
6	#	Question	Asker Name	Answer
7	1	Hello, Greetings of the Day. I am Dr. S. Christopher from NIOT, Chennai, India. I like to know whether M/s.Ruhrpumpen develop very high pressure about about 750 bar for underwater application at the depth of 6000 m	Christopher Stephen	Yes we make pumps up to 1100 barg, but finding the suitable submersible drivers (if you are talking about installing the pumps at 6000m depth) will be a problem
8	2	Since a PD pump provides fixed flow, is the variable speed drive the only way to control the flow then?	Zeeshan Saeed	Yes VSD is one of the options (the best). Another is via mechanical by-pass or a Voith Torque converter (in remote areas or where VSD cannot be used; for example if driver is a diesel engine).
9	3	What is general thumb rule for use of double diaphragm v/s plunger pumps in API 675 applications?	Anonymous Attendee	If the fluid is very toxic then diaphragm pump is the better solution.
10	4	What is the difference between mechanical run test and the performance test? Where we place here FAT and SAT? Thank you in advance	Aurel Mares	Performance test is to measure flow and pressure - the performance of the liquid end. Mechanical run test is for temperature and vibration records and tests the complete pumpset. FAT is test at mfr factory SAT is test at site
11	5	What test is more easier (attractive) to carry (considering time and cost) at the factory: NPSHr or NPIP?	Ruslan Sagitov	NPSH req
12	6	Dear Sir,	Mohammad Jawad Dhailey
13	7	What is the minimum NPSHr for low flow API 674 pump?	nirav patel	Depends on pump size and running speed, typically 3 mt
14	8	can you place two recip pumps in paralel? and if you do what kind of precoutions do you have to take?	diederik ross	Yes of course, we have applications with up to 6. It is highly recommend to perform the Design Approach 2 analysis and drive the pumps via VSD
15	9	Why acoustic damper is used instead of bladder type damper in pumps?	Taufiq Ahmed	To grant higher reliability and reduce maintenance. It is a maintenance free solution, whereas the bladder type requires routine maintenance, recharging with nitrogen and replacement of parts.
16	10	Can (suction / discharge) dampers - be designed too large ? ( which is better than too small dampers ).	Anders G Moller	There is a formula to size dampers depending on no. of plungers (1, 3 or 5) and flow rate. Above a certain volume there is no benefit.
17	11	If this pump is facing leakage issues with the packing, is there an option to upgrade to a mechanical seal?	Mohammad Jawad Dhailey	No, you cannot fit a mechanical seal in plunger pump
18	12	Does double acting configurations is utilised for plunger/piston pumps in API 674/API 675 applications?	Gaurav Chaudhari	Yes API 674 and 675 for large flow rate and low pressure
19	13	What is the significance of external PSV pressure to determine the Hydro Test pressure of Pump Head ?	Anonymous Attendee	The PSV set is equal to design pressure of the head and hydro is 1,5 times the PSV or design pressure
20	14	For abrasive liquids (eg Brine 11 % salt ) - where no external flush is avaialble, can hardcoating of the plunger be applied by RP ?	Anders G Moller	Yes sure, we have done already for a project with Veolia
21	15	with chevron packing is springloaded self adjustment standard?	Anonymous Attendee	No it can be both, spring is better for a non manned plant
22	16	Hi, thank you firstly. I have 3 questions as below: 1-How can we calculate the NPIP of our system? I understand we should announce an available NPSH and NPIP to vendor. 2-How intervals the suction and discharge valves need maintenance or replacing? 3- While having a suction tank, are suction dampers required always?	naghmeh dahi	1) There is a formula in Hydraulic Institute 2) Depending on many factors, typical after 12 months operation 3) Yes unless the suction tank is 1 mt from pump
23	17	maximum temp of diaphragm pump?	Pushpak Akhade	Up to 150 degC with PTFE
24	18	Hello Simon. For parallel setup, is it possible to use different pumps (models)? Would plunger speed have an effect?	Orcun Ozelkok	It is preferable to have same pump models running at equal speed. Same as with centrifugal pumps.
25	19	How is the set pressure determined for the relief valve	Mohammad Jawad Dhailey	As per API 674 is max operating pressure x 1,1, but can be also the design pressure of the piping
26	20	Whether these pumps are available in standard size like centrifugal pumps having min dia. & max dia.? I mean to say is there any max pressure & flow limits are there in these pump models	Anonymous Attendee	The Plunger diameter and stroke length are fixed. So there is no comparison with a centrifugal pump having maximum and minimum diameters. Only the speed is a variable. The maximum flow is determined by the maximum speed. The maximum pressure by the strength of the pump casing.
27	21	what's reason for some client using multiple reciprocating plunger pumps (in parallel) connected to same suction and discharge header...instead of using 1 big pump	Taufiq Ahmed	Lack of availability of very large sizes in the marketplace Any manufacturer will have his own maximum pump size. Typically determined by power (up to 1 MW or 1,5 MW pump.) If you need more flow you are obliged to use multiple pumps in parallel
28	22	Sometimes I have seen leakage recovery line from packing back to pump suction , how configurations unlike plan 11 is decided?	Anonymous Attendee	Yes this is a regular option. It is similar to Plan 13 - Return to Suction See slides 53/54 (extract below)
29
30
31
32
33	Question Report Short Course 39 Second Session
34	Report Generated:	2/27/25 12:19
35	Topic	Webinar ID	Actual Start Time	# Question
36	Session No 39 (Western): An Introduction to Positive Displacement Pumps	863 2821 0160	2/27/25 10:45	29
37	Question Details
38	#	Question	Asker Name	Answer
39	23	Can you back over the power requirements? Isn't pressrue dependent on the fluid density, which is releated to the specific gravity	Gerard Nagle	Well, yes it is. Higher SG will mean higher pressure. BUT per the API Standard, the power formula is calculated with Pressure units not Head units. Hence the SG is not a factor in calculating the power. Remember - PD pumps do not generate pressure, only flow. Pressure is determined by the system.
40	24	Do positive displacement pumps use a mechanical seal?	Uri Parra	No. (Bad luck Uri, you won't be selling us any mechanical seals!)
41	25	For the HP and LP seal fluid to the packing, why is the HP not at the process side, where the pressure is highest, rather then the LP seal fluid as in the diagram?	Gerard Nagle	Good catch!! This slide (51) has the HP & LP connections incorrectly labelled Should be HP on the process side (inboard end), and LP on the Atmospheric side (outboard end)
42				But we had it right in slide 50!
43	26	which test is recommended NPIP or NPSH	Sheldon Solomon	NPSH req is preferred
44	27	What is the acceleration head in this kind of pumps?	Anonymous Attendee	Negligible if a suction damper is installed
45	28	For RDP pumps, do you ussually supply protection due to forced lube oil pump faillure (example: Pressure Switch that stop RDP pump)?	Anonymous Attendee	Yes correct, also a PT nowadays
46	29	How can you change packing by opening the distance piece without pulling pistons/plungers? Are all packing elements split?	Anthony Farole	There is a cartridge to replace. Plunger shall be pulled forwards and the rod dismantled.
47	30	Are there any other instances where a PD pump is preferred over a centrifugal pump besides when precise constant flow rate is required?	Daniel Johnson	1) When you have power issue, RDP grant a 90% mechanical efficiency 2) When discharge pressure is varying a lot
48	31	can you list a few PD pumps pros over the centrifugal pumps in hydrocarbon pipelines. Can they be used as boosters for centrifugal mainline pumps?	Samir Firfire	If the mainline pumps are sized for the main flow and head required by the system, Plunger pumps can be used to boost the flow at the extremes of the system (e.g. branch lines off the main line which are at a higher system pressure.
49	32	Many thanks, Simon. Fabulous, as always.	Anonymous Attendee
50	33	What is the typical rotational design speed of the crankshaft.	Rouvierre Davis	Depends on the pump length of stroke. See table in API 674
51	34	Will the slide deck be sent to us or do we have to go to the website and download?	John Rogers	In the coming days you will get an email giving you the link to download the course materials.
52	35	we have always included a suction strainer as standard on our drawings. is this not allowed?	Daniel Holden	Yes, we do suggest as RP, a Y-strainer with filtration > 300 microns We also suggest it should be a duplex, changeover strainer for ease of maintenance.
53	36	You might mention that using a flow thru suction stabilizer will boost NPSHA by eliminating acceleration head loss!	John Rogers	Thank-you John, Yes it is done all time in our offer remarks
54	37	What is the recirculation line used for?	YAMIL MENA	If you have a fixed speed system then the flow output is fixed. If the system demand varies from this then the only way to vary it is via the bypass line back to the suction tank. VSD is the preferred method of handling variable system demand.
55	38	What are the advantages and disadvantages of a bladder or acoustic type dampener?	YAMIL MENA	See attachment here >>>>>>>>>>>>>>>>>>>> In general, acoustic damper does not have any nitrogen charge and does not need any maintenance so that dampening is always constant and available. But it is more expensive initially.
56	39	We have manufactured some skids for O&G with PD pumps as redundant system (2 in parallel) but only installed dampered pulsation at discharge. We have not considered at suction line, only the Y strainer. Is that correct? Regards	Oliver Valadez	It is prefereable any pump has its own damper on discharge close to pump outlet. Suction damper can be avoided but we need to see the case study. Again a suction damper is always recommeded.
57	40	Thank you	John Rogers
58	41	Ruhrpumpem provides Centrifugal Booster Pumps + Positive Displacement Pumps in a single Skid?	YAMIL MENA	Yes we have done this in few projects
59	42	are torsional analysis provided for larger PD pumps?	Anthony Farole	Yes. This is usual.
60	43	another tip: Locate the PRV upstream of the flow thru acoustic discharge dampener	John Rogers	Noted, thanks
61	44	The PRV can be located downstream of an Appendage gas charged discharge dampener	John Rogers	Noted, thanks
62	45	Is API 674's recommendation to maintain 10% above vapor pressure just a recommendation or is it mandatory?	YAMIL MENA	It is recommended but must be studied case by case
63	46	What is maximal operational temperature the pump can run?	Jorge Garcia	We made projects with high temperature fluids at to 350 degC
64	47	does RP provide other type of PD pumps like screw, diaphagram, gear, etc? Thank you for the presentation	Osvaldo Greco	No, only plunger type up to 1,5 MW
65	48	do you offer cryogenic PD pumps? skidded with insulation>?	Anthony Farole	No, not yet, max we arrive to -30/-40 degC
66	49	Great presentation. Thank you Simon.	Anthony Farole	My pleasure Thank you for attending.
67	50	Thanks you, enjoy the beers	Gerard Nagle	I did!
68	51	Thank you for your time	John Rogers	My pleasure Thank you for attending. And thank you for your contributions.
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100