Laminar vs Orifice 1

[willeng]

Most common manufactured & self built flow benches are of orifice design, including mine.
Can someone put me in the picture regarding Laminar Element flowbenches. I would like to try one to compare the differences.
What are the design considerations.
What can you make the laminar element out of i only want to test with manometers to start with.

How do you take your readings from the element. Eg where do you place the test equipment or manometers in relation to the element.
I have heard you read quality flow-----quality????

Regardless of what Superflow & other manufacturers of orifice flowbenches say about laminar element benches it would be good to try it for myself any help on this would be appreciated.

 

[MaxRaceSoftware]

Laminar Element = disadvantage =>partial accuracy depends on Weather Conditions

Orfice=> no weather corrections, very low cost, very easy to construct..greater Flow Range adaptability !!!

----------------------------------------

Dwyer Instruments Inc
or
Meriam Instruments
search Google,etc





Larry Meaux (maxracesoftware@yahoo.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers
Support Israel - Genesis 12:3

 

LFE is weather specific but, has a linear output and is a lower restriction device. Also can be very accurately calibrated if need be.

 

[MaxRaceSoftware]

http://www.meriam.com/Laminar_Flow_Elements.htm

Download their .PDF files also
very much info for you there

Larry Meaux (maxracesoftware@yahoo.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers
Support Israel - Genesis 12:3

 

[Flowczar]

willeng,

I have used both orifice and LFE benches. My biggest reason for switching to LFE was the data management. I can test faster, including time to test a "calibration" head, using the digital information directly input to pc provided by the LFE.

There are weather considerations and I mitigate them pretty well. I live in the desert and am fortunate enough not to have humidity vary by more than 2%. I control my testing times and run "calibration" parts for flow ranges I am working in. My test numbers repeat, but it's kinda like dynos, numbers are rarely spot on with someone else. The accuracy I see on my bench is around 0.5% full scale (520 cfm at 48" h20). I test mostly at 28, but have learned a lot very quickly when working at the higher deltas, especially in areas under .300" lift. It has been helpful in developing Serdi cutting profiles for some projects, complete with correlating and complementing data from our SF901, so it is doing its' job.

It was a bit of a leap to go to something without a manometer, but I only trust it because I check it religously. The manufacturer was Quadrant Scientific, who ceased to exist about 5 years ago. When I wear it out I'll have to do something else.

I know that the information generated on an SF 1020 is different than that generated on an SF600, some people are publishing data stating which equipment was used. Possibly someone has a comment on this.

 

[MaxRaceSoftware]

Willeng, here are 2 formulas you might be interested
that might help you with your Dyno and Flowbench
weather corrections

Calculates Temperature
there are (2) Loops , either computes the same answer
i prefer the 9 Loop version

'======== Copyright (c) 1995 Larry Meaux , All Rights Reserved ==============
'| |
'| Program Name: REVERSE.BAS , QBasic/QuickBasic version |
'| Date: Sept 29,1995 |
'| Time: 1:00 pm |
'| Purpose: Compute temperature from dewpoint vapor pressure or |
'| from saturation pressure (all in inches Hg.) |
'============================================================================
WIDTH 80 '<--set screen to 80 columns , default
SCREEN 0 '<--set to text screen , default
KEY OFF '<--turn-off 25th line GW-Basic's menu text
VIEW PRINT '<--enable printing on 25th line
LOCATE , , , 7, 7 '<--set cursor to default shape
COLOR 15, 1 '<--bright white on blue
CLS '<--clear entire screen
start:
LOCATE 3, 5
PRINT &quot;Input choices: dewpoint,vapor, or saturation pressure in inches Hg.&quot;;
LOCATE 5, 5
PRINT USING &quot;Pressure inches Hg.= ##.###### &quot;; psat;
LOCATE 5, 38
INPUT psat$: IF LEN(psat$) > 0 THEN psat = VAL(psat$)
IF psat = 0 THEN psat = .5216 '<--default value if no input, (60 deg.F)

x = LOG(29.9213 / psat) '<--29.9213 inches Hg. at sea-level at 59 F
b = psat
a = 672 '<- 672 Rankine, (672 = 460 + 212) , 212 F = boiling pt. H2O
c = 35.9381# '<- Constant , 35.913 works with 671.67 and 459.67 (original)
d = -1.152437# '<- Constant , best constant value for d,(-1.152437 orig.)
logicloop:
FOR cnt = 1 TO 25 '<---- 25 is best value for number of loops
t1 = x - (a - b) * c * (b ^ d)
b = b + t1 / (a * c * d * b ^ (d - 1) - c * (d + 1) * b ^ d)
NEXT cnt
dry1 = psat
FOR cnt = 1 TO 9
dry1 = ((x + (c * (dry1 ^ (-.152437)))) / (a * c)) ^ -.867726392#
NEXT
dryb = (dry1 - 460)

LOCATE 10, 5
psatf = b - 460 '<-Fahrenheit conversion from Rankine degrees (459.67 orig.)
PRINT USING &quot;Temperature =####.#### deg.F (####.#) (2nd formula=####.####)&quot;; psatf; psatf; dryb
GOTO start
=================================================================================



Calculates Pressure


'======== Copyright (c) 1995 Larry Meaux , All Rights Reserved ==============
'| |
'| Program Name: MEAUX.BAS , QBasic/QuickBasic version |
'| Date: Sept 29,1995 |
'| Time: 1:00 pm |
'| Purpose: Compute vapor pressure or |
'| saturation pressure (all in inches Hg.) |
'============================================================================

WIDTH 80 '<--set screen to 80 columns , default
SCREEN 0 '<--set to text screen , default
KEY OFF '<--turn-off 25th line GW-Basic's menu text
VIEW PRINT '<--enable printing on 25th line
LOCATE , , , 7, 7 '<--set cursor to default shape
COLOR 15, 1 '<--bright white on blue
CLS '<--clear entire screen


start:
LOCATE 5, 5
PRINT USING &quot;Dry bulb = ###.## &quot;; dryf;
LOCATE 5, 30
INPUT dryf$: IF LEN(dryf$) > 0 THEN dryf = VAL(dryf$)

dryr = 459.67 + dryf
satp = 29.9213 / (EXP((671.67 - dryr) * 35.913 * (dryr ^ -1.152437)))

LOCATE 8, 5
PRINT USING &quot;Saturation pressure =###.###### inches Hg.&quot;; satp
LOCATE 9, 5
PRINT USING &quot;Saturation pressure =###.###### psia&quot;; satp / 2.036020696#
LOCATE 10, 5
PRINT USING &quot;Saturation pressure =###.###### mm Hg.&quot;; satp * 25.4

GOTO start



Larry Meaux (maxracesoftware@yahoo.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers
Support Israel - Genesis 12:3

 

[willeng]

Larry:
Thanks, your time & effort to respond to this & other forums is appreciated keep it up.