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Pat et al:<br>
<br>
I was asking many of the same questions on this list nearly a year
ago and got some useful information from a variety of places
including Michigan, Berkeley, Draper, Cornell, some of your
colleagues at Princeton and probably a few others. A search of this
mailing list archive from about August 2011 should show those
messages.<br>
<br>
With that information, we've selected flow meters, have them
installed, and are coming up the learning curve in terms of
collecting data, reliability, etc.<br>
<br>
The first important question is whether you have a stainless piping
system or a copper piping system or some of both. In our case, we
have both .... but 90-95% of our usage is on the "house" nitrogen
system piped in copper and a significantly lesser amount is flowing
in our "Ultra High Purity" system piped in stainless (we only have
one LN2 tank ... but at least have some additional purifiers that
make the UHP stuff somewhat better than the house nitrogen.<br>
<br>
However, meters clean enough to go on a copper system are going to
be significantly cheaper than their stainless steel counterparts.
Some of the other labs will likely have more relevant information if
you have a stainless steel system.<br>
<br>
For our system house nitrogen system that is piped in copper, we
have ended up with two different style meters:<br>
<br>
We have "vampire style" meters that clamp on a section of type L
3/4" copper pipe that are built by CDI meters (<a class="moz-txt-link-abbreviated" href="http://www.cdimeters.com">www.cdimeters.com</a>).
They are easily the most cost effective meters that I was able to
find, seem to work well and have large useful flow range. In fact,
the maximum flow that these things can read is HUGE .... like 150
CFM. We've used those primarily in our main facility where we do
see some fairly high flows: when our tube cleaner is running, that
flow meter will hit 60 CFM and we've got others that run 10-15 CFM
day and night. (Aside: I apologize to those of you who are offended
by my use of CFM ... I can think in l/min, but I've never learned to
think in m3/time.) Probably the only downside of these flow meters
is that you need to drill and clamp them onto a length of pipe that
has 20-30 diameters of straight, unobstructed flow upstream and
something like 6-10 diameters downstream. I was worried about
drilling into a actively used section of pipe, so we pre-drilled
sections of pipe about 30" long, deburred and cleaned them, attached
the meters and then cut out an appropriate length of pipe, cleaned
an deburred those ends and then used crimp-on fittings to attach the
new section of metered pipe. We have a total of 24 of those meters
installed and they have on-board totalizers. They also have a
MODBUS interface that we are able to poll over the network using
NET-485 MB interface adapters from Grid Connect
(<a class="moz-txt-link-abbreviated" href="http://www.gridconnect.com">www.gridconnect.com</a>).<br>
<br>
The second style flow meter (I think that we have 14 of these) is
primarily used in the private labs (that we are now able to charge
for nitrogen use) but whose use is typically smaller. In those
applications we selected an Aalborg XFM flow meter with a range of
0-100 l/min. These lower capacity flow meters seem pretty good down
to comparatively low flows. How accurate are they down below 5% of
full flow? I don't know ... but haven't been asked. They are
digital flow meters, have an onboard totalizer, and communicate
using RS-485 (note: while most MODBUS runs over RS-485, RS-485 !=
MODBUS). We have found that we can also communicate with these over
the network, with a slightly different adapter from Grid Connect:
their NET-485 device.<br>
<br>
Note: one NET-485 MB device can be hooked up to as many as 32 CDI
meters and a single NET-485 could be connected to as many as 32 of
the Aalborg meters. Depending on things like fire walls (physical
barriers, not software firewalls ...) we actually have a total of 8
of these network devices to talk to our 38 flow meters.<br>
<br>
For ball park pricing, I'd use:<br>
<br>
CDI 5200 meter including serial communcations option: $550 each.<br>
Aalborg XFM meter (with RS-485 built in): $1100 each.<br>
NET-485 MB: $150 each.<br>
NET-455: $100 each.<br>
<br>
The big cost unknown, I believe is software to communicate with this
stuff. We're doing our own .... so it's free, correct? But not yet
done ...<br>
<br>
There are companies that will sell you turnkey systems, of course,
but that is likely comparatively pricey. Others may be able to
comment on that approach.<br>
<br>
I've rambled on enough, but hope that this will get the discussion
started.<br>
<br>
Thanks,<br>
<br>
John<br>
<br>
On 6/27/2012 1:14 PM, George P. Watson wrote:
<blockquote
cite="mid:0565B0F370443F4CB0D9C1CDDD8533E738BA7F7D@CSGMBX201W.pu.win.princeton.edu"
type="cite">
<div class="moz-text-html" lang="x-western">
<div class="WordSection1">
<p class="MsoNormal" style=""><span style="color: black;">Dear
Labnetwork members,<o:p></o:p></span></p>
<p class="MsoNormal" style=""><span style="color: black;">Our
engineering school Nitrogen cost has risen dramatically
and our method of dividing the cost (mostly guessing
everyone’s usage) has become outdated. We would like to
meter each lab and facility to more fairly assign the
cost. Has anyone had experience installing and using
these meters?
<o:p></o:p></span></p>
<p class="MsoNormal" style=""><span style="color: black;">Can
you recommend a meter capable of maintaining the N2
purity? How much does such a meter cost, and how much is
installation and hookup for remote readout? <o:p></o:p></span></p>
<p class="MsoNormal" style=""><span style="color: black;">What
happens if there is a wide range of N2 flow rate, both
from lab to lab, and at various times within one lab?
Will one meter meet our needs?
<o:p></o:p></span></p>
<p class="MsoNormal" style=""><span style="color: black;">How
do you monitor the N2 use? Do you read flow totals from
the units themselves, or are they connected to a network?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color: black;">Thanks in
advance,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color: black;"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color: black;">Pat<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";">George
Patrick Watson (Pat), Ph.D.</span><span style="font-size:
12pt; font-family: "Times New
Roman","serif";"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";">Director
of Operations</span><span style="font-size: 12pt;
font-family: "Times New
Roman","serif";"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";">PRISM
Micro/Nano Fabrication Laboratory</span><span
style="font-size: 12pt; font-family: "Times New
Roman","serif";"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";">E-Quad
J301A</span><span style="font-size: 12pt; font-family:
"Times New Roman","serif";"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";">Princeton
University</span><span style="font-size: 12pt;
font-family: "Times New
Roman","serif";"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";">Princeton,
NJ 08544</span><span style="font-size: 12pt; font-family:
"Times New Roman","serif";"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";"><a
moz-do-not-send="true"
href="mailto:gwatson@princeton.edu"><span style="color:
blue;">gwatson@princeton.edu</span></a></span><span
style="font-size: 12pt; font-family: "Times New
Roman","serif";"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 10pt;
font-family: "Arial","sans-serif";">(609)
258 4626</span><o:p></o:p></p>
</div>
</div>
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