pre-midterm

Question 1

define the differences between re-use and re-circ systems

Answer 1

re-use: filtered only mechanically, reduces suspended matter, reduces ammonia + CO2 buildup, up to 60% reuse
recirc: return water is treated by multiple filtration techniques, incl’d biofiltration. greatly reduces suspended matter, ammonia is converted to natural form, increased CO2, decreased O2 + Alk. up to 99% recirc.

Question 2

% reuse or recirculated water =

Answer 2

(total amount of reused water/total flow into tanks) x100

Question 3

(equ’n) turnover =

Answer 3

(total volume of the syste)/(total new or makeup water flow rate)

Question 4

3 water quality parameters dependant on water temp

Answer 4

• ammonia
• DO
• viscosity

Question 5

amount of DO in water and rate of O2 transfer from air depend on: (3)

Answer 5

• water temp
• salinity (S=DO decreases)
• degree of saturation

Question 6

Quick definitions:

• Alkalinity
• Hardness
• Viscosity

Answer 6

Al: the buffering capacity of the water
H: measure of calcium and magnesium in the water
V: measure of the fluid’s resistance to shear (stickiness)

Question 7

Name 5 types of pressure

Answer 7

• absolute
• atmospheric
• guage
• burst
• collapse

Question 8

absolute pressure

Answer 8

anything over zero=absolute pressure

Question 9

atmospheric pressure

Answer 9

ATM pressure exerted on the exterior surface of the vessel

Question 10

gauge pressure

Answer 10

the difference between the absolute pressure and the atmospheric pressure in relation to a vessel. (difference between internal and external pressure of vessel)

Question 11

burst pressure

Answer 11

amount of pressure a vessel can withstand until it bursts.

Question 12

collapse pressure

Answer 12

the outside of the vessel has more pressure than the inside, causing collapse inwardly

Question 13

Manometer

Answer 13

tube that is connected one side to your vessel and 1 side to the atmosphere

Question 14

regarding pressure, what happens when you:

• increase wall thickness
• increase pipe diameter

Answer 14

WT: increase in max working pressure
PD: decrease in max working pressure

Question 15

regarding pressure, what happens when you use an:

• oversized pipe
• undersized pipe

Answer 15

O: increase in cost, decrease in max work pressure, possible settling of solids in system
U: possibly limited flow but can handle increased pressure

Question 16

name the three types of flow, which one to avoid, and their associated Reynolds numbers

Answer 16

laminar (0-2000)
transitional (2000-4000) avoid
turbulent (>4000)

Question 17

what three factors is water hammer dependant on?

Answer 17

fluid’s velocity, pipe diameter, material

Question 18

name 5 ways to minimize water hammer

Answer 18

• reduce velocity to < 1.5/s
• reduce # of valves + fittings
• open/close valves slowly
• add valve @ outlet of pump
• add water hammer arrestor