Stenner pumps and tanks

[vetman85]

In order to replace my Rainbow 320 chlorine tab feeder, I've been looking at the Liquidator (which seems to have problems with variable speed pumps and requires hooking it into the suction side of the pump) and the Stenner pump with associated tank. After much to'ing and fro'ing with the Stenner folks, I have discovered the tanks they recommend have tank lids that allow air into the tank while the pump is on (to compensate for the suction caused by the pump). When the pump is off the chlorine is essentially open to the atmosphere. If I were to use this system, I'd like a tank that has some sort of check valve that allows air in when the pump is on and closes when the pump is off....preventing the chlorine gas from just bleeding off ot the atmosphere. Anyone got a system set up like that?

Perhaps it's time to look into an SWG system...?

 

[mikespoolfl]

The link will show a picture of my set up and cost. Where the black tube goes in the tank I left a little play in the hole. This allows a little air to get in. My set up pumps just under a ounce a minute.


Did I pull the trigger too fast?

 

[JoyfulNoise]

I'm not sure I understand why you think air is a problem? Chlorine bleach is much more strongly affected by UV light and heat. An air relief orifice is going to be of little effect.

Many people like Stenner pumps and I agree that they are useful but it is important to shield the tank from excessive heat and light. So if you do consider a Stenner pump, also consider the location of the tank relative to your equipment pad and make allowances for mitigating sun/heat exposure.

 

[vetman85]

Air isn't the problem. In my case,while the tank would sit on the north side of the house and mostly in the shade, it does get upwards of 100 here in July/August. So, in any case, it will probably be 90 in the shade. Seems if the tank is not air-tite when the pump is off, chlorine gas will be leaking from the tank....adding to the degradation of the chlorine in the tank.

Perhaps an idea would be to use a bit of the Liquidator technology and add an inch or so of water (gently) to the top of the bleach layer, creating a buffer between the bleach and the atmosphere.

 

[JoyfulNoise]

Air isn't the problem. In my case,while the tank would sit on the north side of the house and mostly in the shade, it does get upwards of 100 here in July/August. So, in any case, it will probably be 90 in the shade. Seems if the tank is not air-tite when the pump is off, chlorine gas will be leaking from the tank....adding to the degradation of the chlorine in the tank.

Perhaps an idea would be to use a bit of the Liquidator technology and add an inch or so of water (gently) to the top of the bleach layer, creating a buffer between the bleach and the atmosphere.

Ah, I see your concern -

If I were to use this system, I'd like a tank that has some sort of check valve that allows air in when the pump is on and closes when the pump is off....preventing the chlorine gas from just bleeding off ot the atmosphere. Anyone got a system set up like that?

Chlorine gas release is not possible from bleach unless it is mixed with a strong acid, such as muriatic acid. The main decomposition reactions for bleach are as follows -

3 OCl(-) ---> ClO3(-) + 2 Cl(-)

Hypochlorite ion ---> Chlorate ion + chloride ion

AND

2 OCl(-) ---> O2(g) + 2 Cl(-)

Hypochlorite ion ---> Oxygen gas + chloride ion

Chlorates will further decompose according to the reaction -

2 ClO3(-) ---> 3 O2(g) + 2Cl(-)

Chlorate formation is typically minimal, so the major gas produced by decomposing bleach is oxygen. The rate of decomposition is strongly dependent on hypochlorite concentration and temperature, so liquid chlorine containers (10%-15%) typically have vented caps on them to allow oxygen gas buildup to bleed off.

 

[vetman85]

Looks good. Looks like you're injecting into the lower plug area on the tab feeder...correct? On hot days, does it smell like chlorine near the tank??

 

[vetman85]

Apologies if I'm getting my replies mixed up....new to the forum. This is to JoyfulNoise's excellent description of the chemical degradation of bleach. You answered my concerns (guess I should have paid closer attention in chemistry class). I'm certainly not concered about venting oxygen. Thanks everyone. Back to looking at this setup versus converting to an SWG system.

 

[JoyfulNoise]

Apologies if I'm getting my replies mixed up....new to the forum. This is to JoyfulNoise's excellent description of the chemical degradation of bleach. You answered my concerns (guess I should have paid closer attention in chemistry class). I'm certainly not concered about venting oxygen. Thanks everyone. Back to looking at this setup versus converting to an SWG system.

The reason why you smell a "chlorine odor" from bleach is that is does have a small vapor pressure. From this MSDS for Hasa Brand 12.5% LC, the vapor pressure of bleach is ~12 mmHg. Bleach has a "fresh" odor to it that will hit your nostrils but quickly become pungent. The reason for this is when the hypochlorite ion hits your mucous membranes, it reacts with the organic compounds in your nose and forms chloramines. Those chloramines are what you register as "pungent" and "that bad pool smell".