Working principle hot air diaphragm pump, understanding and questions - Page 1
Forum section: electronics / beginners

author: suryaputhra
author_rank: Regular Contributor
timestamp: September 02, 2016, 04:49:11 pm
content: I have observed in many hot air rework stations with diaphragm pump comes with reservoir tank, I have seen some models without reservoir tank. This tank called by many names.1. By Hakko it is called Sound proof tank.2. By Chinese makers it is called Buffer3. By some maker reservoir tank4. By some makers called noise isolating tankDiaphragm pump works by to and pro oscillation diaphragm so the air output is pulsating. In blower models air output is gentle and not pulsating. Is this reservoir tank is used to reduce pulsating output of the air, if so why Hakko called it just sound proof tank. Is it just to reduce resonating noise from diaphragm pump. Pls see the first picture.By just placing a tank one can not achieve smooth flow of the air. There should be a pressure valve and a hydraulic liquid should be there to achieve the results. This setup is seen in house hold and industrial and is called auxiliary reservoir tank attached to diaphragm pump.But in this case such valve or hydraulic liquid setup not seen, so what is the purpose of this mysterious tank in hot air rework station.-suryaputhra

author: rrinker
author_rank: Super Contributor
timestamp: September 02, 2016, 07:16:42 pm
content: Having a tank of some sort will reduce the pulsations, and maybe remove a direct "puff puff" sound out of the heat gun, hence the "sound proof tank" although I suspect the various names the tank is called is more an issue of language translation than anything. You are correct, it can't get rid of all the pulsations, and it can't function as a reservoir without an inlet valve and some sort of pressure control. There are larger diaphragm compressors used for paint guns and air tools that have an actual reservoir which do work in the traditional manner where the pump will shut off once a set pressure is reached and the air then is released from the tank until the pressure drops low enough to trigger the pump back on.

author: Brumby
author_rank: Unknown
timestamp: September 03, 2016, 01:09:42 am
content: Quote from: rrinker on September 02, 2016, 07:16:42 pmExactly. It is the pneumatic equivalent of a capacitor. The bigger the tank, the less "puff puff" (ripple) will be produced, but it will take more to "charge" it up.QuoteThe terms can vary because of translation issues, but also from different basic descriptions that may be used because of cultural influences or varying levels of understanding.

author: sleemanj
author_rank: Super Contributor
timestamp: September 03, 2016, 01:25:59 am
content: Are the inlet and outlet port diameters the same? Or maybe the tubing or subsequent path for air from the "sound proof tank" to the nozzle tip is otherwise more constricted than the inlet. In such a case you have effectively a capacitor with no resistor for charging it, and a resistor for discharging it.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 03, 2016, 05:37:08 am
content: its difficult to make conclusion from your photos. tubing of that size will not make any "capacitor" effect at near atmospheric pressure. otoh anything with enclosed wall is eligible to be called a sound proof chamber, somebody may nitpick esp audiophool guys, they expect 100% sound proof only to say sound proof. but if the chamber let the 90% sound out, it means it is a 10% sound proof chamber ymmv.

author: suryaputhra
author_rank: Regular Contributor
timestamp: September 03, 2016, 07:42:30 am
content: @sleemanj Inlet and outlet port size is the same. My main concern is that this particular setup will not work as a full sound proofing or to reduce pulsating air output fully. It just reduces the pulsating affect by diffusing the air in the tank but there is no mechanism for filling the tank full and releasing air in the controlled manner and with constant pressure. This is just like a silencer in two stroke engines.I have seen some models without tank.My question is does this pulsating air output have any significant affect on hot air rework?if so what are the effects if not what are the technical reasons.-suryaputhra

author: IanB
author_rank: Super Contributor
timestamp: September 03, 2016, 07:52:13 am
content: Air is compressible, therefore an air tank can act as a pressure reservoir and reduce pressure fluctuations. As noted above, it is the pneumatic analog of an electrical capacitor. The diaphragm pump produces fluctuations that we want to smooth out.From electrical theory we know that a capacitor alone cannot smooth out ripples: it must be combined with a resistor or inductor to produce a filter. The same is true in pneumatics. The air reservoir alone is not enough, but when combined with a resistance it can form a smoothing filter. In the hot air station the resistance is formed from the outlet air pipe and hot air nozzle. The resistance to air flow in this path, when combined with the air reservoir, produces the effective "RC" filter that is desired to smooth the air flow.

author: suryaputhra
author_rank: Regular Contributor
timestamp: September 03, 2016, 08:31:33 am
content: @IanB, Excellent I have convinced with your explanation technically, so the pipe and nozzle act as a pressure valve and hydraulic liquid like in regular diaphragm pumps with auxiliary reservoir tank. Yes I have observed this phenomenon in practical , when we put our finger in front of the nozzle obstructing the air flow a little bit pulsating is reduced as you said this acted as a pressure valve. My second question isdoes this pulsating air output have any significant affect on hot air rework? if so what are the effects if not what are the technical reasons.How about adding tank to non tank models, what could be the sizing.-suryaputhra

author: suryaputhra
author_rank: Regular Contributor
timestamp: September 04, 2016, 10:44:22 am
content: Hi can someone put light on my previous post.-suryaputhra