Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 13-10-2015, 18:11   #121
Registered User
 
LakeSuperior's Avatar

Join Date: Jan 2008
Boat: Teak Yawl, 37'
Posts: 1,581
Images: 7
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by LakeSuperior View Post
valhalla360 - gph is a volume flow rate and if the fluid is identified then it is equivalent to a mass flow rate (density X volume).
When I reread I realized I wasn't precise. The density X volume gives the mass and per unit time gives the mass flow rate.
__________________

__________________
LakeSuperior is offline   Reply With Quote
Old 13-10-2015, 20:25   #122
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,705
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by jwcolby54 View Post
Easy if we know the time required to fill.
Exactly!

So "If you know GPH you can calculate tank volume" is not true. You also need other information.

Thus we again establish that the statement: "GPH is a volumetric measurement" is false.
__________________

__________________
StuM is online now   Reply With Quote
Old 13-10-2015, 21:44   #123
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by StuM View Post
Exactly!

So "If you know GPH you can calculate tank volume" is not true. You also need other information.

Thus we again establish that the statement: "GPH is a volumetric measurement" is false.
Not so. If I have a flow of 1000 gph, I know that in 24 hours I would need at least a 24,000 gallon tank to hold that flow. Also a 1000GPH of water at STP has a weight of 8330 pounds at the end of one hour, or 199,920 pounds after 24 hours.

So it is very much a volumetric measurement. That you defend your position even when faced with physics text, clearly available anywhere on the net, astounds me. It also shows your not an engineer.
__________________
sailorchic34 is online now   Reply With Quote
Old 13-10-2015, 22:03   #124
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 4,016
Amps v Amp hours v Amps/Hr

Guys, can we stop with the insults? It does nothing to further the argument.

GPH is not a volume measurement. It is a flow rate or a rate of change in volume. For example, if a 100 gallon tank requires 10 hours to empty then we know the average flow is 10GPH. But if all we know is the 10GPH number without knowing the time and the initial conditions (starting volume) then we cannot tell anything about the net volume.

Similarly AH per hour is a fairly useless measure describing the rate of change in energy flow. Without also knowing the initial charge and the time values we can say nothing about the absolute energy level. So AH per hour is not that useful unit of measure that helps figure anything in boat DC systems.

AH per day can be useful because we have implied a time period of 24 hours. So if this number is negative then we know the batteries will eventually be discharged completely. If it is positive we know the batteries will be charged full every day.
__________________
transmitterdan is offline   Reply With Quote
Old 13-10-2015, 22:31   #125
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by transmitterdan View Post
Guys, can we stop with the insults? It does nothing to further the argument.

GPH is not a volume measurement. It is a flow rate or a rate of change in volume.
It was not my intent to insult Stu. Just making a simple observation.


From Wikipedia: red highlight by me.

"Volumetric flow rate


Volume flow rate Common symbols
,
In physics and engineering, in particular fluid dynamics and hydrometry, the volumetric flow rate, (also known as volume flow rate, rate of fluid flow or volume velocity) is the volume of fluid which passes per unit time; usually represented by the symbol Q. The SI unit is m3/s (cubic metres per second). Another unit used is sccm (standard cubic centimeters per minute).
In US Customary Units and British Imperial Units, volumetric flow rate is often expressed as ft3/s (cubic feet per second) or gallons per minute (either U.S. or imperial definitions).
Volumetric flow rate should not be confused with volumetric flux, as defined by Darcy's law and represented by the symbol q, with units of m3/(m2Ěs), that is, mĚs−1. The integration of a flux over an area gives the volumetric flow rate.


Fundamental definition

Volumetric flow rate is defined by the limit:[1]


I.e., the flow of volume of fluid V through a surface per unit time t.
Since this is only the time derivative of volume, a scalar quantity, the volumetric flow rate is also a scalar quantity."


So I again say that GPM or GPM is a volumetric measurement, that is a measure of volume per unit time. Any physic text will agree with me.

From Engineersedge.com

Fluid Volumetric Flow Rate Equation
The volumetric flow rate (V ) of a system is a measure of the volume of fluid passing a point in the system per unit time. The volumetric flow rate can be calculated as the product of the cross sectional area (A) for flow and the average flow velocity (v).
If area is measured in square feet and velocity in feet per second, Equation 3-1 results in volumetric flow rate measured in cubic feet per second. Other common units for volumetric flow rate include gallons per minute, cubic centimeters per second, liters per minute, and gallons per hour.
Example:
A pipe with an inner diameter of 4 inches contains water that flows at an average velocity of 14 feet per second. Calculate the volumetric flow rate of water in the pipe.



Yes it's a Flow rate. But that flow rate has a volume component.

GPH has a time unit, so it can define volume per time just by itself. If you say 10 GPH for 20 minutes that also gives a know volume . But if all you have is 10 GPH its still 10 gallons in an hour. I used GPM or GPH all day long in sizing piping systems. It is a volumetric flow rate.

BTW this is basic engineering 101, which perhaps explains my earlier comment.
__________________
sailorchic34 is online now   Reply With Quote
Old 13-10-2015, 23:21   #126
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,705
Re: Amps v Amp hours v Amps/Hr

One last one and then I give up.

You are completely focused on one word "volume" and somehow think that that word is the crux of the dispute. It is not. In fact it is totally irrelevant.

It doesn't matter whether we talk about gallons, nautical miles or coulombs.

When you talk about any unit with a single time component such as gph,
knots or amps you are talking about a RATE. You are not talking about a volume, distance or number of coulombs, but a RATE at which a liquid, vehicle or current is "moving". (Please don't try to side track us again trying to define movement as only to do with distance. I am using it in a more general sense).

Let's take it right back to the beginning and ignore your claims of superior "engineering knowledge" and vast experience with gallons.

The POINT is not about what sort of thing we are measuring. It is about your continually conflating "units of quantity" and "rates of change" regardless of what is being measured - and your inability to comprehend that amps per hour or amps/hr is not a valid way to talk about power consumption.

As Pauli allegedly said about another physicist's work: "'That is not only not right, it is not even wrong".

Not even wrong - RationalWiki
__________________
StuM is online now   Reply With Quote
Old 13-10-2015, 23:54   #127
Registered User

Join Date: Apr 2013
Posts: 4,861
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by jwcolby54 View Post
Easy if we know the time required to fill.
That's the point.

If I tell you the volume of a tank if 50gallons, you know the volume.
If I tell you the hose is putting in 5gpm, you haven't got a clue that the volume of the tank is without more information (such as how long it takes to fill).

5gpm is a flow rate. Just like speed isn't a distance, flow rates aren't volumes.
__________________
valhalla360 is offline   Reply With Quote
Old 13-10-2015, 23:56   #128
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,327
Re: Amps v Amp hours v Amps/Hr

@SC34,
Can you describe the difference to me (if any) between volume (say gallon) and volume flow rate (say GPH).
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 14-10-2015, 00:02   #129
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by StuM View Post
One last one and then I give up.

You are completely focused on one word "volume" and somehow think that that word is the crux of the dispute. It is not. In fact it is totally irrelevant.

It doesn't matter whether we talk about gallons, nautical miles or coulombs.

When you talk about any unit with a single time component such as gph,
knots or amps you are talking about a RATE. You are not talking about a volume, distance or number of coulombs, but a RATE at which a liquid, vehicle or current is "moving". (Please don't try to side track us again trying to define movement as only to do with distance. I am using it in a more general sense).

Let's take it right back to the beginning and ignore your claims of superior "engineering knowledge" and vast experience with gallons.

The POINT is not about what sort of thing we are measuring. It is about your continually conflating "units of quantity" and "rates of change" regardless of what is being measured - and your inability to comprehend that amps per hour or amps/hr is not a valid way to talk about power consumption.
Wait, here all I've been doing is responding to you where you posted the following:

"So "If you know GPH you can calculate tank volume" is not true. You also need other information.

Thus we again establish that the statement: "GPH is a volumetric measurement" is false. " So your position is GPH is not Volumetric.


Yet all I've done is posted several references that say exactly the opposite of what you say. Yes it's important, as it proves my position that you have been badgering me with for many many days. Please reread my links above. GPM and GPH is a volumetric flow rate that's based on the volume of fluid which passes per unit time. That's what it is, not a speed or velocity or whatever.

As to Rate, lordy

This is what you posted above: "You are not talking about a volume, distance or number of coulombs, but a RATE at which a liquid, vehicle or current is moving".

No. Please reread the links I posted YES, GPH is a rate, but per the links, GPH is a rate of volume of gallons per minute. It's not a speed or acceleration. I've posted two definitions that quite clearly define what a GPH is.

So can we agree that GPH is a volumetric flow rate and not a speed or velocity or whatever your position was. A rate can be a speed or distance traveled, but GPH is not that rate.


I'm using GPH as its defined in physics and engineering textbooks, How else could I use it. GPH is not a velocity change or a acceleration change and its most definitely not a speed of flow. That would be in units of FPS or MPS, etc.

It's quite simply volumetric flow rate per unit time. Yes its a Rate, but that rate is the volume in gallons per time unit. Nothing more or less.

Lets get this part behind us and THEN we can move to amperes, Coulombs and fun with electrons.
__________________
sailorchic34 is online now   Reply With Quote
Old 14-10-2015, 00:03   #130
Registered User

Join Date: Apr 2013
Posts: 4,861
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by sailorchic34 View Post
It was not my intent to insult Stu. Just making a simple observation.


From Wikipedia: red highlight by me.

"Volumetric flow rate


Volume flow rate Common symbols
,
In physics and engineering, in particular fluid dynamics and hydrometry, the volumetric flow rate, (also known as volume flow rate, rate of fluid flow or volume velocity) is the volume of fluid which passes per unit time; usually represented by the symbol Q. The SI unit is m3/s (cubic metres per second). Another unit used is sccm (standard cubic centimeters per minute).
In US Customary Units and British Imperial Units, volumetric flow rate is often expressed as ft3/s (cubic feet per second) or gallons per minute (either U.S. or imperial definitions).
Volumetric flow rate should not be confused with volumetric flux, as defined by Darcy's law and represented by the symbol q, with units of m3/(m2Ěs), that is, mĚs−1. The integration of a flux over an area gives the volumetric flow rate.


Fundamental definition

Volumetric flow rate is defined by the limit:[1]


I.e., the flow of volume of fluid V through a surface per unit time t.
Since this is only the time derivative of volume, a scalar quantity, the volumetric flow rate is also a scalar quantity."


So I again say that GPM or GPM is a volumetric measurement, that is a measure of volume per unit time. Any physic text will agree with me.

From Engineersedge.com

Fluid Volumetric Flow Rate Equation
The volumetric flow rate (V ) of a system is a measure of the volume of fluid passing a point in the system per unit time. The volumetric flow rate can be calculated as the product of the cross sectional area (A) for flow and the average flow velocity (v).
If area is measured in square feet and velocity in feet per second, Equation 3-1 results in volumetric flow rate measured in cubic feet per second. Other common units for volumetric flow rate include gallons per minute, cubic centimeters per second, liters per minute, and gallons per hour.
Example:
A pipe with an inner diameter of 4 inches contains water that flows at an average velocity of 14 feet per second. Calculate the volumetric flow rate of water in the pipe.



Yes it's a Flow rate. But that flow rate has a volume component.

GPH has a time unit, so it can define volume per time just by itself Volume per time is not a volume. It is a flow rate. If you say 10 GPH for 20 minutes that also gives a know volume You are adding information to the flow rate to determine volume. But if all you have is 10 GPH its still 10 gallons in an hour Only if the flow continues for an hour which a flow rate doesn't tell you. I used GPM or GPH all day long in sizing piping systems With you misunderstanding of the concept, I really question this.. It is a volumetric flow rate.

BTW this is basic engineering 101, which perhaps explains my earlier comment.
It's very simple, once you change the units by adding the "/time" component, it is an instantaneous flow rate. It is not a volume. This is not academic nitpicking. This is a simple but key difference between a volume and a flow rate that you clearly don't grasp.

Saying you can use calculate the volume using the flow rate ALONG WITH OTHER INFORMATION is not the same as saying a flow rate is volume.
__________________
valhalla360 is offline   Reply With Quote
Old 14-10-2015, 00:10   #131
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,705
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by sailorchic34 View Post

So can we agree that GPH is a volumetric flow rate.
Happy too. I've never disputed it. What I have disputed is your insistence that it is a Volume. Which is a totally different thing.

Can we now agree that GPH is not a volume?
__________________
StuM is online now   Reply With Quote
Old 14-10-2015, 00:10   #132
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by Wotname View Post
@SC34,
Can you describe the difference to me (if any) between volume (say gallon) and volume flow rate (say GPH).
sure
Volume is a displacement measurement, such as gallons, where one gallon displaces a volume of .1336 cubic feet, give or take


Volume flow rate: is a measure of the volume of fluid passing a point in the system per unit time

From Engineersedge.com


Fluid Volumetric Flow Rate Equation
The volumetric flow rate (V ) of a system is a measure of the volume of fluid passing a point in the system per unit time. The volumetric flow rate can be calculated as the product of the cross sectional area (A) for flow and the average flow velocity (v).
If area is measured in square feet and velocity in feet per second, Equation 3-1 results in volumetric flow rate measured in cubic feet per second. Other common units for volumetric flow rate include gallons per minute, cubic centimeters per second, liters per minute, and gallons per hour.
Example:
A pipe with an inner diameter of 4 inches contains water that flows at an average velocity of 14 feet per second. Calculate the volumetric flow rate of water in the pipe.


So GPH for example is volume of fluid passing a point in the system per unit of time. where gallons is simply a volume.
__________________
sailorchic34 is online now   Reply With Quote
Old 14-10-2015, 00:13   #133
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by StuM View Post
Happy too. I've never disputed it. What I have disputed is your insistence that it is a Volume. Which is a totally different thing.

Can we now agree that GPH is not a volume?
I would love it, yet the defination of a GPH is a measure of the volume of fluid passing a point in the system per unit time.
__________________
sailorchic34 is online now   Reply With Quote
Old 14-10-2015, 00:23   #134
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,812
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by valhalla360 View Post
It's very simple, once you change the units by adding the "/time" component, it is an instantaneous flow rate. It is not a volume. This is not academic nitpicking. This is a simple but key difference between a volume and a flow rate that you clearly don't grasp.

Saying you can use calculate the volume using the flow rate ALONG WITH OTHER INFORMATION is not the same as saying a flow rate is volume.
Yet the example listed in my post gave a flow rate in cubic feet per second. That is the example listed 1.22 cubic feet per second. That cubic feet thingy is a volune of fluid passing in one second. 1.22 Cubic feet is 9.1256 gallons per second. So there is a volume component to CFS or GPM or GPH.
__________________
sailorchic34 is online now   Reply With Quote
Old 14-10-2015, 01:46   #135
Registered User

Join Date: Apr 2013
Posts: 4,861
Re: Amps v Amp hours v Amps/Hr

Quote:
Originally Posted by sailorchic34 View Post
Yet the example listed in my post gave a flow rate in cubic feet per second. That is the example listed 1.22 cubic feet per second. That cubic feet thingy is a volune of fluid passing in one second. 1.22 Cubic feet is 9.1256 gallons per second. So there is a volume component to CFS or GPM or GPH.
This reminds me of when I was a kid and my Mom took us to visit Aunt Mimi in the home. She explained that no mater what you tell her, she isnt' going to grasp that Uncle Frank is gone and if you persist, you will just upset her.

So to take from quote from the fridge threat:

How many GPH does a 20 liter jerrycan hold?
Your response: Somewhere between 0 and 4.45 ish.

I'm going to respond, with that's a very nice 0-4.45gph jerry can you have. I hope it serves you well.
__________________

__________________
valhalla360 is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Engine hours how many over 10k hours? stevensuf Engines and Propulsion Systems 1 10-05-2015 20:50
50 Amp on Boat to Two 30 amps on Dock..BUT mtmilam Electrical: Batteries, Generators & Solar 4 21-04-2015 22:26
how many amp hours from a solar panel or wind generator viking69 Electrical: Batteries, Generators & Solar 11 12-12-2006 04:14
How Many Amp Hours? ssullivan Electrical: Batteries, Generators & Solar 15 10-10-2005 20:25



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 17:29.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.