HYDRO-ZONE, INC.
17800 TELEGRAPH, ROMULUS, MI 48174
PHONE: (734) 247-4488 FAX (734) 247-4489
HARDNESS DROP TEST PROCEDURE
Code:
HZ921202
A. Low Total Hardness Test:
SAMPLE SIZE
50 ml
100 ml
DROP EQUIVALENCY
0.5 ppm as CaCO3
0.25 ppm
“
The test utilizes an EDTA drop count titration for low total hardness
(soluble, free calcium & magnesium) testing. An inhibited, substituted
amine buffer & calmagite indicator are added to the sample. A purple
color forms if hardness is present above 0.2 ppm, and a more pink to red
color if hardness is above 1 ppm. A blue color develops if hardness is
absent from the sample. Dissolved metals and other constituents can
interfere with an accurate test. For more information refer to Standard
Methods; APHA, AWWA, & WPCF, 17th Ed..
1. Collect a water sample and measure, using the graduated cylinder,
the appropriate sample size into a clean titration flask:
a. 50 mls for 1 drop = 0.5 ppm
b. 100 mls for 1 drop = 0.25 ppm
2. Add 10 drops of HZ080105, Hardness Buffer and mix well by swirling.
(The pH of the solution should be 10.0 to 10.5, adjust if necessary
by adding more HZ080105.)
3. Add 10 drops of HZ080120, Hardness Indicator and mix by swirling.
4. Add HZ080147, Low Hardness
drop, until the color just
Record the number of drops
report the total hardness,
a.
b.
Note 1:
Note 2:
Note 3:
DT a drop at a time, mixing after each
changes from purple or red to blue.
& multiply by the appropriate factor to
as ppm (mg/L) CaCO3, in the sample:
0.5 X number of drops for 50 ml sample.
0.25 X number of drops for 100 ml sample.
The detection limit is approximately 0.2 ppm total
hardness. Any value below the detection limit should
be reported as less then 0.2 ppm.
As the endpoint is approached, titrate more slowly to
allow time for the reaction to take place. This is
important with samples below 20 deg. C, or hardness
below 2 ppm. Hot samples should be cooled to below
40 deg. C before titrating.
Metal ions such as aluminum, cobalt, copper, iron, and
nickel can poison the hardness indicators. They produce
off colors, indistinct or fading endpoints, or no end
point at all. Masking agents may be required for proper
test results - call for assistance.
1
HYDRO-ZONE, INC.
17800 TELEGRAPH, ROMULUS, MI 48174
PHONE: (734) 247-4488 FAX (734) 247-4489
Code HZ921202
B. TOTAL HARDNESS TEST:
SAMPLE SIZE
10 ml
20 ml
100 ml
DROP EQUIVALENCY
20 ppm as CaCO3
10 ppm
“
2 ppm
“
The procedure utilizes an EDTA drop count titration for total hardness
(calcium & magnesium) testing. An inhibited, substituted amine buffer &
calmagite indicator are added to the sample. A purple color forms if
hardness is present above 0.2 ppm, and a more pink to red color if
hardness is above 1 ppm. A blue color develops if hardness is absent
from the sample. Dissolved metals and other constituents can interfere
with an accurate test. For more information refer to Standard Methods;
APHA, AWWA, & WPCF, 17th Ed..
1. Collect a water sample and measure, using the graduated cylinder,
the appropriate sample size into a clean titration flask:
a. 10 mls for 1 drop = 20 ppm
b. 20 mls for 1 drop = 10 ppm
c. 100 mls for 1 drop = 2.0 ppm
2. Add 10 drops of HZ080105, Hardness Buffer and mix well by swirling.
NOTE: The pH of the solution should be 10.0 to 10.5, adjust if
necessary by adding more HZ080105.)
3. Add 5 drops of HZ080120, Hardness Indicator and mix by swirling.
Add 10 drops to the 100 ml sample.
4. Add HZ080152, Hardness DT a drop at a time, mixing after each
drop, until the color just changes from purple or red to blue.
Record the number of drops & multiply by the appropriate factor to
report the total hardness, as ppm (mg/L) CaCO3, in the sample:
a.
b.
c.
20 X number of drops for 10 mls
10 X number of drops for 20 mls
2.0 X number of drops for 100 mls
NOTE 1:
As the endpoint is approached, titrate more slowly to
allow time for the reaction to take place. This is
important with samples below 20 deg. C, or hardness
below 10 ppm. Hot samples should be cooled to below
40 deg. C before titrating.
NOTE 2:
Metal ions such as aluminum, cobalt, copper, iron, and
nickel can poison the hardness indicators. They produce
off colors, indistinct or fading endpoints, or no end
point at all. Masking agents may be required for proper
test results - call for assistance.
2
HYDRO-ZONE, INC.
17800 TELEGRAPH, ROMULUS, MI 48174
PHONE: (734) 247-4488 FAX (734) 247-4489
Code HZ921202
C. CALCIUM HARDNESS TEST:
SAMPLE SIZE
10 ml
20 ml
100 ml
DROP EQUIVALENCY
20 ppm as CaCO3
10 ppm
“
2 ppm
“
The procedure utilizes an EDTA drop count titration for calcium hardness
testing. Sodium hydroxide and calcon indicator are added to the sample.
A red color forms if calcium hardness is present. A blue color develops
if calcium hardness is absent from the sample. Dissolved metals and
other constituents can interfere with an accurate test. For more
information refer to Standard Methods; APHA, AWWA, & WPCF, 17th Ed..
1. Collect a water sample and measure, using the graduated cylinder,
the appropriate sample size into a clean titration flask:
a. 10 mls for 1 drop = 20 ppm
b. 20 mls for 1 drop = 10 ppm
c. 100 mls for 1 drop = 2.0 ppm
2. Add 10 drops of HZ190159, NaOH, 4N, mix well by swirling.
(The pH of the solution should be 12 to 13, adjust if necessary
by adding more HZ190159.)
3. Add 1 scoop (0.1 gm) of HZ030115, Calcium Indicator, mix and
dissolve
by swirling. Add two scoops to the 100 ml sample.
4. Add HZ080152, Hardness DT a drop at a time, mixing after each
drop, until the color just changes from red to blue. Record the
number of drops & multiply by the appropriate factor to report the
calcium hardness, as ppm (mg/L) CaCO3, in the sample:
a.
b.
c.
20 X number of drops for 10 mls
10 X number of drops for 20 mls
2.0 X number of drops for 100 mls
NOTE 1:
As the endpoint is approached, titrate more slowly to
allow time for the reaction to take place. This is
important with samples below 20 deg. C, or hardness
below 10 ppm. Hot samples should be cooled to below
40 deg. C before titrating.
NOTE 2:
Metal ions such as aluminum, cobalt, copper, iron, and
nickel can poison the hardness indicators. They produce
off colors, indistinct or fading endpoints, or no end
point at all. Masking agents may be required for proper
test results - call for assistance.
3
HYDRO-ZONE, INC.
17800 TELEGRAPH, ROMULUS, MI 48174
PHONE: (734) 247-4488 FAX (734) 247-4489
Reagents and Components:
1
1
1
1
1
2
1
1
1
2
2
1
1
X
X
X
X
X
X
X
X
X
X
X
X
X
Plastic Case w/insert
2 OZ DB, HZ080105-02, Hardness Buffer
2 OZ DB, HZ080120-02, Hardness Indicator
2 OZ DB, HZ080151-02, Low Hardness DT
2 OZ DB, HZ080152-02, Hardness DT
1 OZ DB, HZ190159-01, NaOH 4N
10 GM, 030115-10, Calcium Indicator
HZ554100, Scoop, 0.1 GM
HZ507140, Graduated Cylinder, Plastic, 100 ml
10-042-5E, Flask, Plastic/Screw Cap, 250 ml
10-042-5C, Flask, Plastic/Screw Cap, 125 ml
9587, Colorphast pH Strips, 7.5-14
Instructions, Hardness Drop Test Procedure
Issued: 8/01
Revised: 10/06
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