Lab 1 Partial

Lab 1 Partial!

As a replacement, note the supplies provided to you on the apparatus.

Extra:

1. Stopwatch
2. Water (for Q)
3. Balance
4. Scale

This is a step-by-step process for you to use the weight-time method to measure volumetric flow rate :)

First, note that you're calculating delta t right now. You'll need to add weight W and after these two markers, you'll derive M(dot) and Q.

1. The first the is that you'll want to send water through the apparatus with the other side left open. This creates a steady-state operation for you to observe.
2. Next, you'll want to use your balance to represent the weight measured on your scale. In order to do so, you'll need to overbalance the scale until it hits the bottom.
3. After that, close the end of the apparatus and continue to let water flow through.
4. Do this until the scale rebalances itself; really make sure to wait until this happens before starting the stopwatch
5. Start the stopwatch!
6. Add some weight to your apparatus (as discussed before) to represent the actual weight measured on your scale. You might be wondering what it represents, well it depends on what weight you choose. I tend to choose one that is 1% of the full weight (so add a couple pounds to represent 200lbs).
7. Let the scale rebalance again after adding the two pounds (you're doing great)
8. As soon as the scale hits the top (as it should at some point) stop the watch.

Right now, you have delta t and M. That's great! Now, you need to measure the manometer to get your heights and the Bourdon gages to get your pressures!

Be precise, look close at the measurements...

For the Manometer:

1. Check both sides of where the mercury is (left and right), and sum the height differential and you'll get your delta h.

For the Bourdon gages:

1. Check the top left gage, it'll be in kPa and make sure to read the outer number to give you something precise; now, you have your pressure points.

IMPORTANT: do this procedure nine more times with different flow rates and you should get a linear relationship for the manometer and Bourdon gages.

Here, you've done all of the work to plot the relationship between the pressure differential within the Bourdon Gage measurements that you made and the manometer measurements. Here is what is should look like.

Note, there is a small deviation in time measurements for you, but that's alright. The relationship should still be linear, though.

This is very important to analyze. Note which one seems more reliable (follows the trend better). It seems that the manometer is a bit more reliable from the plot (that is normal, but there should be some variation.

Analyze at which points one is more reliable than the other. For instance, for Q's from 0 to 0.0003, it's a shake-up. But from 0.0004 onwards, the manometer seems to be more accurate.

Let me tell you the explanation for any differences between the two methods: user error and instrument precision. Firstly, you did your best (that is fine), but it is important to recognize that you're unable to get the most precise measurement from the readings; it's just not possible. Secondly, the gages didn't move much, right? They're stable, but aren't as precise as the ticks on the manometer. The manometer, although precise in measurement, varied a lot during the process; the mercury oscillated a bit. This is normal, but a contributing factor for a difference in the reliability of the methods.

These are just a few checks for finishing the labs. You need to get a few of these data points for future analysis and future use of the apparatus to measure volumetric flow rate. Use the equations you used for your plot.

1. Use shortest time measurement to find flow rate (Qs)
2. 0.0342ft^3/s, where t = 46.81s
3. Use the longest time measurement to find flow rate (Ql)
4. 0.0121ft^3/s, where t = 132.75s

Now, calculate the precision (e) of your measurements. Here is the formula: e = (Qs - Ql)/(0.5(Qs + Ql)). For instance, I received 0.95 (multiply by 100) = 95%. That is not good.

The precision found in typical engineering calculations is around 10%. Mine is way above it, which means I made a few errors during the process. You can do better! I wish you luck!