5.3 amps actually produces 7 grams per hour.
5.3 amps is 5.3 coulombs/second. One Faraday is one mole of electrons and is about 96,485 coulombs. So 5.3 amps is 5.3/96485 = 5.5x10
-5 moles of electrons per second. The chemical reaction that produces chlorine is:
2Cl
- --> Cl
2(g) + 2e
-
and then the chlorine dissolves in water:
Cl
2(g) + H
2O --> HOCl + H
+ + Cl
-
so that the net (half) reaction is:
Cl
- + H
2O --> HOCl + H
+ + 2e
-
So it takes 2 electrons to produce one molecule of hypochlorous acid (HOCl). So the 5.3 amps produces 5.3/96485/2 = 2.75x10
-5 moles of chlorine per second. The "grams of chlorine" is based on the weight of chlorine gas (all chlorine "ppm" measurements are based on that as well) which is 70.906 grams/mole so the 5.3 amps produces 2.75x10
-5 * 70.906 = 1.95x10
-3 grams per second.
1.95x10
-3 grams/sec * 3600 seconds/hour = 7.0 grams chlorine per hour
If you were producing 33 grams chlorine per hour, that would be enough to raise the FC level by 0.87 ppm in 10,000 gallons every hour. Instead, the 7 grams per hour is equivalent to raising the FC level by 0.18 ppm in 10,000 gallons per hour.
I'm not disputing that your cell may be outputting 33 grams per hour, but the output current to do that isn't 5.3 amps. Since 5.3 amps produces 7.0 grams of chlorine per hour then it takes 5.3 * 33 / 7 = 25 amps to produce 33 grams per hour.
On your own website describing the SMC30T for example (see
this link) it says it outputs 33 grams per hour with an input of 240 Volts and 300 Watts. I already calculated that it would take 25 amps to produce 33 grams chlorine per hour so that translates to 300/25 = 12.0 Volts if there were no losses (i.e. 100% efficiency). With some loss of efficiency, this could be 7.5 volts as you described. If I look at most of your models, it appears that they all operate at varying (by model) low output voltage since that makes the input power (watts) and voltage (240V) consistent with the gram/hour ratings. Of course, some variation is due to varying efficiencies and rounding of specifications. Specifically, we have the following all at 240V input. I used a conversion of 1 gram/hour requiring 0.76 amps and then derived a maximum output voltage assuming 100% efficiency of input to output power and that all the electrolysis is going towards the production of chlorine (i.e. no side reactions) at the anode. If there is less efficiency, then the voltages could be lower (with some of the "missing" input power going to heat losses and side reactions).
Model ... Input Watts ... Output Chlorine Rate ... Required Output Current ... Maximum Output Voltage
SMC20T, SMCA20, SMCE20 ... 190 Watts ... 22 grams/hour ... 16.7 Amps ... 11.4 Volts
SMC30T, SMCA30, SMCE30 ... 300 Watts ... 33 grams/hour ... 25.1 Amps ... 12.0 Volts
AMCINI ... 50 Watts ... 5 grams/hour ... 3.8 Amps ... 13.2 Volts
AC15 ... 240 Watts ... 15 grams/hour ... 11.4 Amps ... 21.1 Volts
AC20 ... 304 Watts ... 20 grams/hour ... 15.2 Amps ... 20.0 Volts
AC25 ... 344 Watts ... 25 grams/hour ... 19.0 Amps ... 18.1 Volts
AC35 ... 420 Watts ... 35 grams/hour ... 26.6 Amps ... 15.8 Volts
AC50 ... 650 Watts ... 50 grams/hour ... 38.0 Amps ... 17.1 Volts
AC100 ... 1400 Watts ... 100 grams/hour ... 76.0 Amps ... 18.4 Volts
RPMINI ... 50 Watts ... 5 grams/hour ... 3.8 Amps ... 13.2 Volts
RP15 ... 240 Watts ... 15 grams/hour ... 11.4 Amps ... 21.1 Volts
RP20 ... 240 Watts ... 20 grams/hour ... 15.2 Amps ... 15.8 Volts
RP25 ... 240 Watts ... 25 grams/hour ... 19.0 Amps ... 12.6 Volts
RP36 ... 240 Watts ... 35 grams/hour ... 26.6 Amps ... 9.0 Volts
RP50 ... 600 Watts ... 50 grams/hour ... 38.0 Amps ... 15.8 Volts
RP64 ... 330 Watts ... 64 grams/hour ... 48.6 Amps ... 6.8 Volts
RP92 ... 650 Watts ... 92 grams/hour ... 69.9 Amps ... 9.3 Volts
Richard