Re: [psas-airframe] Orifices!!!

[Kristin Travis]

Rob and I figured out the coefficient (~0.36) for the McMaster orifice (
https://www.mcmaster.com/#2712t47/=1agjtnf) and the hole size (3/8") we
need to drill in it. (drilling the hole will change the coefficient but
this is the most conservative). This will result in ~200 psi drop across
the orifice at the 3 lbm/s flowrate. If we use two of these transducers
https://www.omega.com/pressure/pdf/PX119.pdf the error should remain
significantly below 10% leaving us room to add error by drilling the hole
in the orifice.

On Tue, Nov 28, 2017 at 1:01 PM, Bertrand DeChant 
wrote:

> Undesirable conditions should result in failsafe(likely shutdown and
> Purge). Mitigation of sensing error(extreme) should be considered. This is
> not an issue for pintle testing where pressure data can be calibrated and
> used only for water.
>
> On Nov 28, 2017 12:55 PM, "Joseph Shields"  wrote:
>
>> > If all else fails in this regard, we're out about $100 as opposed to
>> $$$ for a gox safe transducer.
>>
>> If you got misleading pressure measurements from it, what other parts
>> might get damaged? Like, say you got a low measurement and opened some
>> upstream valve in response.
>>
>> On Nov 28, 2017 12:49 PM, "Bertrand DeChant" 
>> wrote:
>>
>> Absolutely, the ones that were previously specc'd for the engine should
>> work well in this pressure range. These would be recycled for the igniter
>> (engineer chamber pressure) and the engine (fuel manifold pressure). I'll
>> look at the specs and point out expected factors of error this afternoon or
>> evening. As for an oxygen environment it seems the previous plan to
>> standoff/pack is the industry standard and reasonable for our budgeting
>> needs. If all else fails in this regard, we're out about $100 as opposed
>> to $$$ for a gox safe transducer.
>>
>> On Nov 28, 2017 12:40 PM, "Erin Schmidt"  wrote:
>>
>>> Hi guys,
>>> I'm sick and won't be coming to the meeting tonight. For what it is
>>> worth here are my thoughts:
>>> -I think we should aim for <10% measurement uncertainty.
>>>--This probably is expensive to achieve over our range of flow rates
>>> with most kinds of flow meters (though we could do more research here).
>>>--The dP tranducer has error +/- 5 psig, if we pick the larger
>>> orifice we will have 50% measurement uncertainty at the 1 lb/s flowrate. If
>>> we want to lower the uncertainty by increasing the pressure drop, then we
>>> need to factor in the added expense of the higher-pressure dP sensor (note
>>> that even the 260psi dP sensor would have ~17% error @ 1 lb/s).
>>>--Probably our best bet is to use 2 transducers in lieu of a single
>>> dP transducer. Some of the ashcroft/omega ones easily meet our requirements
>>> and we can move to a bigger pressure drop to improve accuracy. I also like
>>> this because the sensors won't be 1-offs and potentially could be recycled
>>> into other projects. Bert and/or Jacob, was there a sensor you liked for
>>> LFETS applications? If so can you send me a link to the spec sheet?
>>>--An alternate option is to relax either our range of flow rates or
>>> measurement accuracy requirements. Thoughts about this Kristin?
>>>
>>>
>>> Ad astra,
>>> Erin Schmidt
>>>
>>> On Sun, Nov 26, 2017 at 10:10 PM, Kristin Travis <
>>> theeblueorc...@gmail.com> wrote:
>>>
 dP presure transducers get pretty expensive if you go above 250 psi.
 Maybe a flowmeter costs less than the orifice + the dP transducer + the
 fittings and tubes for the dP transducer? Or if we drill out the orifice to
 have a larger hole, can we drop the dP below 250psi (assuming it's 250 psi
 dP across the transducer)?

 Let's go over this on Tuesday

 On Thu, Nov 23, 2017 at 11:59 AM, Musil Mark 
 wrote:

> Ok, I will await your modified order.
>
> On Nov 23, 2017 11:27, "Erin Schmidt"  wrote:
>
>> The dp treasurer will not work for the range of flow rates required
>> (either the pressure is too high for the sensor, or the measurement
>> error>50%).  Let's respec it.
>>
>> On Nov 22, 2017 7:14 PM, "Mark Musil"  wrote:
>>
>>> The current purchase order is attached. Nothing has been ordered.
>>> Let me know what needs changed.
>>>
>>> On Nov 22, 2017 5:04 PM, "Kristin Travis" 
>>> wrote:
>>>
 Hi Erin,

 The dP transducer we spec-ed is this https://www.omega.com/pre
 ssure/pdf/PX26.pdf

 I cc'd Mark Musil, did you order this yet Mark?

 Thanks,
 Kristin


 On Wed, Nov 22, 2017 at 4:34 PM, Erin Schmidt 
 wrote:

> BTW have you guys ordered any of the 'general purpose' pressure
> transducers yet? I'd like to have a look at the spec. sheet.
>

Re: [psas-airframe] Orifices!!!

[Joseph Shields]

> If all else fails in this regard, we're out about $100 as opposed to $$$
for a gox safe transducer.

If you got misleading pressure measurements from it, what other parts might
get damaged? Like, say you got a low measurement and opened some upstream
valve in response.

On Nov 28, 2017 12:49 PM, "Bertrand DeChant" 
wrote:

Absolutely, the ones that were previously specc'd for the engine should
work well in this pressure range. These would be recycled for the igniter
(engineer chamber pressure) and the engine (fuel manifold pressure). I'll
look at the specs and point out expected factors of error this afternoon or
evening. As for an oxygen environment it seems the previous plan to
standoff/pack is the industry standard and reasonable for our budgeting
needs. If all else fails in this regard, we're out about $100 as opposed to
$$$ for a gox safe transducer.

On Nov 28, 2017 12:40 PM, "Erin Schmidt"  wrote:

> Hi guys,
> I'm sick and won't be coming to the meeting tonight. For what it is worth
> here are my thoughts:
> -I think we should aim for <10% measurement uncertainty.
>--This probably is expensive to achieve over our range of flow rates
> with most kinds of flow meters (though we could do more research here).
>--The dP tranducer has error +/- 5 psig, if we pick the larger orifice
> we will have 50% measurement uncertainty at the 1 lb/s flowrate. If we want
> to lower the uncertainty by increasing the pressure drop, then we need to
> factor in the added expense of the higher-pressure dP sensor (note that
> even the 260psi dP sensor would have ~17% error @ 1 lb/s).
>--Probably our best bet is to use 2 transducers in lieu of a single dP
> transducer. Some of the ashcroft/omega ones easily meet our requirements
> and we can move to a bigger pressure drop to improve accuracy. I also like
> this because the sensors won't be 1-offs and potentially could be recycled
> into other projects. Bert and/or Jacob, was there a sensor you liked for
> LFETS applications? If so can you send me a link to the spec sheet?
>--An alternate option is to relax either our range of flow rates or
> measurement accuracy requirements. Thoughts about this Kristin?
>
>
> Ad astra,
> Erin Schmidt
>
> On Sun, Nov 26, 2017 at 10:10 PM, Kristin Travis  > wrote:
>
>> dP presure transducers get pretty expensive if you go above 250 psi.
>> Maybe a flowmeter costs less than the orifice + the dP transducer + the
>> fittings and tubes for the dP transducer? Or if we drill out the orifice to
>> have a larger hole, can we drop the dP below 250psi (assuming it's 250 psi
>> dP across the transducer)?
>>
>> Let's go over this on Tuesday
>>
>> On Thu, Nov 23, 2017 at 11:59 AM, Musil Mark 
>> wrote:
>>
>>> Ok, I will await your modified order.
>>>
>>> On Nov 23, 2017 11:27, "Erin Schmidt"  wrote:
>>>
 The dp treasurer will not work for the range of flow rates required
 (either the pressure is too high for the sensor, or the measurement
 error>50%).  Let's respec it.

 On Nov 22, 2017 7:14 PM, "Mark Musil"  wrote:

> The current purchase order is attached. Nothing has been ordered. Let
> me know what needs changed.
>
> On Nov 22, 2017 5:04 PM, "Kristin Travis" 
> wrote:
>
>> Hi Erin,
>>
>> The dP transducer we spec-ed is this https://www.omega.com/pre
>> ssure/pdf/PX26.pdf
>>
>> I cc'd Mark Musil, did you order this yet Mark?
>>
>> Thanks,
>> Kristin
>>
>>
>> On Wed, Nov 22, 2017 at 4:34 PM, Erin Schmidt  wrote:
>>
>>> BTW have you guys ordered any of the 'general purpose' pressure
>>> transducers yet? I'd like to have a look at the spec. sheet.
>>>
>>> Ad astra,
>>> Erin Schmidt
>>>
>>> On Tue, Nov 21, 2017 at 10:13 PM, Erin Schmidt 
>>> wrote:
>>>
 Guys,
 I want your feedback on this orifice: Brass, 2712T47, 0.047"
 diameter, 1/2"X1/2" NPT ($24.69)
 *https://www.mcmaster.com/#2712t47/=1ad0hiu
 *

 Gets us a 30 psi drop at the low end of our flow range (still not
 sure if 30 psi is too much for flow measurement accuracy, the 
 corresponding
 drop will be 120 psi @ 2 lb/s  and 260 psi @ 3 lb/s). This implies we
 need a maximum tank pressure of around 344 psi. If we go up to a 0.063"
 diameter the range is a bit more reasonable (10, 35, 80 psi @ 1, 2, 3
 lb/s). Have we had any luck speccing the delta-p transducer yet? 
 Knowing
 the accuracy of the measurement will help us make a more informed 
 decision
 about the orifice...


 Ad astra,
 Erin Schmidt

 On Tue, Nov 14, 2017 at 10:43 PM, Erin Schmidt 

Re: [psas-airframe] Orifices!!!

[Erin Schmidt]

Hi guys,
I'm sick and won't be coming to the meeting tonight. For what it is worth
here are my thoughts:
-I think we should aim for <10% measurement uncertainty.
   --This probably is expensive to achieve over our range of flow rates
with most kinds of flow meters (though we could do more research here).
   --The dP tranducer has error +/- 5 psig, if we pick the larger orifice
we will have 50% measurement uncertainty at the 1 lb/s flowrate. If we want
to lower the uncertainty by increasing the pressure drop, then we need to
factor in the added expense of the higher-pressure dP sensor (note that
even the 260psi dP sensor would have ~17% error @ 1 lb/s).
   --Probably our best bet is to use 2 transducers in lieu of a single dP
transducer. Some of the ashcroft/omega ones easily meet our requirements
and we can move to a bigger pressure drop to improve accuracy. I also like
this because the sensors won't be 1-offs and potentially could be recycled
into other projects. Bert and/or Jacob, was there a sensor you liked for
LFETS applications? If so can you send me a link to the spec sheet?
   --An alternate option is to relax either our range of flow rates or
measurement accuracy requirements. Thoughts about this Kristin?


Ad astra,
Erin Schmidt

On Sun, Nov 26, 2017 at 10:10 PM, Kristin Travis 
wrote:

> dP presure transducers get pretty expensive if you go above 250 psi. Maybe
> a flowmeter costs less than the orifice + the dP transducer + the fittings
> and tubes for the dP transducer? Or if we drill out the orifice to have a
> larger hole, can we drop the dP below 250psi (assuming it's 250 psi dP
> across the transducer)?
>
> Let's go over this on Tuesday
>
> On Thu, Nov 23, 2017 at 11:59 AM, Musil Mark 
> wrote:
>
>> Ok, I will await your modified order.
>>
>> On Nov 23, 2017 11:27, "Erin Schmidt"  wrote:
>>
>>> The dp treasurer will not work for the range of flow rates required
>>> (either the pressure is too high for the sensor, or the measurement
>>> error>50%).  Let's respec it.
>>>
>>> On Nov 22, 2017 7:14 PM, "Mark Musil"  wrote:
>>>
 The current purchase order is attached. Nothing has been ordered. Let
 me know what needs changed.

 On Nov 22, 2017 5:04 PM, "Kristin Travis" 
 wrote:

> Hi Erin,
>
> The dP transducer we spec-ed is this https://www.omega.com/pre
> ssure/pdf/PX26.pdf
>
> I cc'd Mark Musil, did you order this yet Mark?
>
> Thanks,
> Kristin
>
>
> On Wed, Nov 22, 2017 at 4:34 PM, Erin Schmidt  wrote:
>
>> BTW have you guys ordered any of the 'general purpose' pressure
>> transducers yet? I'd like to have a look at the spec. sheet.
>>
>> Ad astra,
>> Erin Schmidt
>>
>> On Tue, Nov 21, 2017 at 10:13 PM, Erin Schmidt  wrote:
>>
>>> Guys,
>>> I want your feedback on this orifice: Brass, 2712T47, 0.047"
>>> diameter, 1/2"X1/2" NPT ($24.69)
>>> *https://www.mcmaster.com/#2712t47/=1ad0hiu
>>> *
>>>
>>> Gets us a 30 psi drop at the low end of our flow range (still not
>>> sure if 30 psi is too much for flow measurement accuracy, the 
>>> corresponding
>>> drop will be 120 psi @ 2 lb/s  and 260 psi @ 3 lb/s). This implies we
>>> need a maximum tank pressure of around 344 psi. If we go up to a 0.063"
>>> diameter the range is a bit more reasonable (10, 35, 80 psi @ 1, 2, 3
>>> lb/s). Have we had any luck speccing the delta-p transducer yet? Knowing
>>> the accuracy of the measurement will help us make a more informed 
>>> decision
>>> about the orifice...
>>>
>>>
>>> Ad astra,
>>> Erin Schmidt
>>>
>>> On Tue, Nov 14, 2017 at 10:43 PM, Erin Schmidt 
>>> wrote:
>>>
 https://neutrium.net/fluid_flow/discharge-coefficient-for-no
 zzles-and-orifices/

 Ad astra,
 Erin Schmidt

>>>
>>>
>>
>
>
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