TCEQ Class B Surface Water B Test
Material / TCEQ Class B Water
License Exam Already Passed!!
What is chlorine Demand? - ✔✔✔ANSWER-The amount of chlorine used up
to completely react with the water and its suspended or dissolve material
What is chlorine residual? - ✔✔✔ANSWER-When all the demand of the water
is met any additional chlorine produces a chlorine residual
What is chlorine dosage? - ✔✔✔ANSWER-Demand plus residual is the
chlorine dosage. Chlorine Dosage = Demand + Residual
What determines rate of disinfection? - ✔✔✔ANSWER-Chlorine
concentration and contact time determines the rate and degree of disinfection. If
concentration increases, the time can be reduced; if concentration is reduced the
time must be increased.
How does temperature effect chlorine effectiveness? - ✔✔✔ANSWER-
Chlorine effectiveness is greater at higher temperatures, up to the point that
chlorine volatizes. At low temperature, chlorine is more stable, but disinfection
time increases.
,Is removing turbidity important for disinfection? - ✔✔✔ANSWER-Turbidity
must be removed to low levels by sedimentation and filtration to allow chlorine to
contact pathogens.
What happens to dissolved solids on contact with chlorine? - ✔✔✔ANSWER-
Dissolved solids are oxidized on contact further reinforcing the importance of
contact time.
No residual is formed until reducing agents are destroyed. What are examples of
reducing agents? - ✔✔✔ANSWER-Manganese, iron, turbidity, organic matter,
ammonia, or nitrates
What the 4 stages of the Chlorine Demand Curve chart? - ✔✔✔ANSWER-
Stage 1: No residual is formed because inorganic demand destroys the chlorine.
(Flat Line)
Stage 2: Monochloramines are formed as chlorine combines with organics
containing ammonia (rising curve). The chlorine to ammonia weight ratio at this
point is 5:1. Combined and total residual increases, chloro-organics are formed.
Stage 3: Increasing chlorine dosage (failing curve) to a chlorine/ammonia weight
ratio of 7.6:1 destroys chloramines and chloro-organics. Combined decreases and
free chlorine increases.
,Stage 4: Enough chlorine is added to reduce all demand. The combined residual
remains the same, but free residual increases with dosage. This stage is called
"breakpoint" chlorination. The chlorine to ammonia ratio of 10:1 satisfies all
demand and disinfects the distribution system. ( second rising curve)
What is the difference between free chlorine and combined chlorine
(chloramines/chlorine-ammonia) systems? - ✔✔✔ANSWER-Free chlorine is
more powerful than combined chlorine, but combined chlorine lasts longer.
- combined chlorine requires a 60-minute detention time while free chlorine
requires 10 minutes.
-If combined residual is replaced by a free residual, less taste and odor in the water
usuals occurs.
- if combined residual is used : ph and temperature must be monitored closely and
the residual adjusted accordingly. For example, as the temperature decreases the
combines residual must be increased. Free residual does not require such
monitoring in the 6.0 - 8.0 pH range. Free chlorine residual concentration is not
affected by temperature changes.
What is the minimum chlorine residual at the far reaches of the system for both
free and combined? - ✔✔✔ANSWER-Free chlorine residual = .2mg/L
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free chlorine or chloramine
residual of 4 mg/L as a running average. Limiting residuals reduces disinfection
byproducts such as trihalomethanes and haloacetic acids. These byproducts,
consumed over a long period of time, may cause cancer.
, What are the proper techniques for chlorine cylinder storage? -
✔✔✔ANSWER-- secure the ton cylinders in a horizontal position and move
with a lifting bar and hoist. Never roll them
- 150lbs cylinders shall be chained to rigid support and keep capped unless in use.
- Check all chlorine systems for leaks before putting into service with a 10%
ammonia solution. Household ammonia is not approved. When ammonia contacts
chlorine gas white smoke results.
What are the steps to do before entering a room with a chlorine leak? -
✔✔✔ANSWER-1: notify other operators and have standby help for possible
notification of emergency personnel
2: Be trained in emergency procedures and have knowledge of chlorinators, tools,
and ammonia use.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
What is the maximum withdrawal rate for 150lbs chlorine cylinders? -
✔✔✔ANSWER-The maximum sustained gas withdrawal rate for 150lbs
cylinders (vacuum transmission) is 1lbs per day per degree F.
The equivalent rate for ton cylinders (vacuum transmission) is 8 lb per day per
degree F.
Material / TCEQ Class B Water
License Exam Already Passed!!
What is chlorine Demand? - ✔✔✔ANSWER-The amount of chlorine used up
to completely react with the water and its suspended or dissolve material
What is chlorine residual? - ✔✔✔ANSWER-When all the demand of the water
is met any additional chlorine produces a chlorine residual
What is chlorine dosage? - ✔✔✔ANSWER-Demand plus residual is the
chlorine dosage. Chlorine Dosage = Demand + Residual
What determines rate of disinfection? - ✔✔✔ANSWER-Chlorine
concentration and contact time determines the rate and degree of disinfection. If
concentration increases, the time can be reduced; if concentration is reduced the
time must be increased.
How does temperature effect chlorine effectiveness? - ✔✔✔ANSWER-
Chlorine effectiveness is greater at higher temperatures, up to the point that
chlorine volatizes. At low temperature, chlorine is more stable, but disinfection
time increases.
,Is removing turbidity important for disinfection? - ✔✔✔ANSWER-Turbidity
must be removed to low levels by sedimentation and filtration to allow chlorine to
contact pathogens.
What happens to dissolved solids on contact with chlorine? - ✔✔✔ANSWER-
Dissolved solids are oxidized on contact further reinforcing the importance of
contact time.
No residual is formed until reducing agents are destroyed. What are examples of
reducing agents? - ✔✔✔ANSWER-Manganese, iron, turbidity, organic matter,
ammonia, or nitrates
What the 4 stages of the Chlorine Demand Curve chart? - ✔✔✔ANSWER-
Stage 1: No residual is formed because inorganic demand destroys the chlorine.
(Flat Line)
Stage 2: Monochloramines are formed as chlorine combines with organics
containing ammonia (rising curve). The chlorine to ammonia weight ratio at this
point is 5:1. Combined and total residual increases, chloro-organics are formed.
Stage 3: Increasing chlorine dosage (failing curve) to a chlorine/ammonia weight
ratio of 7.6:1 destroys chloramines and chloro-organics. Combined decreases and
free chlorine increases.
,Stage 4: Enough chlorine is added to reduce all demand. The combined residual
remains the same, but free residual increases with dosage. This stage is called
"breakpoint" chlorination. The chlorine to ammonia ratio of 10:1 satisfies all
demand and disinfects the distribution system. ( second rising curve)
What is the difference between free chlorine and combined chlorine
(chloramines/chlorine-ammonia) systems? - ✔✔✔ANSWER-Free chlorine is
more powerful than combined chlorine, but combined chlorine lasts longer.
- combined chlorine requires a 60-minute detention time while free chlorine
requires 10 minutes.
-If combined residual is replaced by a free residual, less taste and odor in the water
usuals occurs.
- if combined residual is used : ph and temperature must be monitored closely and
the residual adjusted accordingly. For example, as the temperature decreases the
combines residual must be increased. Free residual does not require such
monitoring in the 6.0 - 8.0 pH range. Free chlorine residual concentration is not
affected by temperature changes.
What is the minimum chlorine residual at the far reaches of the system for both
free and combined? - ✔✔✔ANSWER-Free chlorine residual = .2mg/L
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free chlorine or chloramine
residual of 4 mg/L as a running average. Limiting residuals reduces disinfection
byproducts such as trihalomethanes and haloacetic acids. These byproducts,
consumed over a long period of time, may cause cancer.
, What are the proper techniques for chlorine cylinder storage? -
✔✔✔ANSWER-- secure the ton cylinders in a horizontal position and move
with a lifting bar and hoist. Never roll them
- 150lbs cylinders shall be chained to rigid support and keep capped unless in use.
- Check all chlorine systems for leaks before putting into service with a 10%
ammonia solution. Household ammonia is not approved. When ammonia contacts
chlorine gas white smoke results.
What are the steps to do before entering a room with a chlorine leak? -
✔✔✔ANSWER-1: notify other operators and have standby help for possible
notification of emergency personnel
2: Be trained in emergency procedures and have knowledge of chlorinators, tools,
and ammonia use.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
What is the maximum withdrawal rate for 150lbs chlorine cylinders? -
✔✔✔ANSWER-The maximum sustained gas withdrawal rate for 150lbs
cylinders (vacuum transmission) is 1lbs per day per degree F.
The equivalent rate for ton cylinders (vacuum transmission) is 8 lb per day per
degree F.
