Heart of the Matter

Student Worksheet:
Valve Functions

Step One: Observe the provided ball valve to observe how the ball rotates to restrict flow of fluids.   

Questions:
1. What did you notice about the ball inside as the knob or handle was turned?  How would this impact the fluid that passed through it?

2. What advantages did you find in this type of valve?

3. What applications can you think of to apply this type of valve?

4. Which valve might be better for controlling the flow of fresh water?  Waste water?  Why?

Step Two: As a team, assemble a mini valve system for running water, using parts provided to you.  This can be done in a sink, or outdoors.  Assemble the valve provided to the pipes, and answer the questions below.  You should have a gate valve, two lengths of pipe, two hose caps, a head plug, some water and a funnel. First, attach each end of the gate valve to a piece of ¾" pipe.  Turn the valve to prevent water flowing through, then add water to one and gradually turn the valve so that only a drop or two of water can pass through the further pipe end.  Then try different combinations of parts examining the ability of water to flow.

Questions:
1. Can you completely block the water from flowing?  If so, why?

2. What happens if there is a hose cap on one end of one pipe? If you have water completely filling the two tubes, can you shut off the valve?  

3. How about if you have two hose caps in place?  Does the pressure change?  Why or why not?

      Heart of the Matter

Student Worksheet:
Valve Functions (continued)

4. How does the functionality of the gate valve differ from the ball valve? 

5.  Which type of valve do you think would best control the flow of water, if either?  Why?

6.  Which type of valve do you think would be best to control the flow of blood?  Why?

Step Three:
Now that you have tried out valves, and read about the strengths and weaknesses of the three main types of mechanical heart valves, work as a team to engineer an improvement for future mechanical heart valves.  Attach a drawing or sketch of your proposed component part, and answer the questions below:

What aspect of current mechanical hearts did you choose to improve? Why?	What materials or parts will you eliminate or add?	How will this new design address the shortcoming you identified?	How do you think your new design will impact society? Why?	

				

4.  Present your suggested new design, including sketches, to the class.