FISSUREMAN TECHNICAL INFO BLOG

August 16, 2010

California Dredging Moratorium

Filed under: Uncategorized — fissureman @ 11:49 am

At least two out-of-state hand dredge competitors have recently added either a quote from an official source, some statement of compliance or other self proposed opinion as to whether suction hand dredges are legal to use in California due to the temporary moratorium on dredging permits that was enacted a while back.
 
I agree with the basic premise expressed by any statement that hand dredges are still legal in California waterways. There is nothing in either the original dredging permit requirements or within the recently imposed moratorium wording that specifically states that hand operated prospecting equipment is not legal for use – suction or otherwise.
 
The temporary moratorium was placed on new permits for the use of gasoline powered suction dredging equipment while leaving hand-operated equipment legal for use.
 
Unfortunately, however, enforcement is still left up to the local ranger(s) that patrol the area that you might be prospecting to judge or determine what is going to be allowed for use when it comes to equipment type.
 

I beleive it is most prudent and more responsible to not try and determine if any equipment is legal for use as I am not a lawyer (and I suspect neither are you).  

Individual rangers could possibly give you a problem – or worse - a ticket and/or potentially confiscate your equipment leaving you holding the bag and a fine to fight in court.

The best action anyone of us can take is to contact the supervising ranger station in charge of the land we wish to prospect and ask first about using the hand dredge or suction equipment we plan to use. If the supervising ranger’s office agrees with you that it is OK for use (and they should – provided it is not state park land) then request a signed and dated statement from the supervisor that will be suitable for presentation to any overzealous, uninformed individual ranger that you might encounter. 

UPDATE!!!  8/24/10

The following was sent to me today from one of my customers. I have removed his last name for privacy purposes. He kindly provided the following emails for me to post as a prime example of what I have stated above.

 

Dennis:

In lieu of the CA SB670 Law I decided to seek clarification in the use of a “Hand Operated Dredge” from Mark Stopher who is in charge of the EIR that SB670 calls for.  Here is a forwarded email along with his response.  I thought you might be able to use this on your web site……… Disclaimer….. I am not a Lawyer so this is not legal advice !!!!

Thanks

Mark 

 

August 21, 2010                                                                                                                                               

Dear Mr Stopher: 

        
I am writing to you for clarification to see if the operation of what I
will call a “Hand Powered Dredge” attached to a sluice box and
placed in a waterway would constitute a violation of SB670. 

A “Hand Powered Dredge” for the purposes in this letter is simply a
hand powered piston pump with a check valve that allows water along with
other gold bearing river bottom gravels to sucked into the pump and be
diverted into a hose which would then be attached to a sluice box or
other concentrating device and placed in a  waterway.   Please refer to
the following photograph #1 for clarification.

Should your response conclude that the operation the above described
equipment in a  waterway would be in violation of SB670.  Then I would
like to ask that if the effluent from the above pump and hose were first
collected into a bucket and then transported to a sluice or other
concentrating device would that be in violation of SB670.  Please refer
to Photo #2 for clarification.

It is my intention to carry your letter of clarification with me in the
field in order to assist any law enforcement officers with clarification
into this matter.  Please respond via e-mail.

Respectfully

Mark

Rewood City CA 94062

On Tue, 8/24/10, Mark Stopher wrote:

From: Mark Stopher
Subject: Re: Hand Powered Dredges
To: “Mark xxxx”
Date: Tuesday, August 24, 2010, 11:33 AM

Mark

It is DFG’s view that operation of your hand powered dredge is not a
violation of SB 670. Although you propose to operate it in a live
stream, and it does rely on a vacuum to remove material from the bed of
the stream, Fish and Game Code section 5653.1(d) states ” This section
does not prohibit or restrict nonmotorized recreational mining
activities, including panning for gold”.

While a portion of the Code arguably applies to your proposed actions,
the quoted subsection provides an exception for nonmotorized dredging.

Mark Stopher
Environmental Program Manager
California Department of Fish and Game
601 Locust Street
Redding, CA 96001

voice 530.225.2275
fax 530.225.2391
cell 530.945.1344


BE Safe – BE Smart – BE Proactive!


July 13, 2010

SANDMAN valve reliability testing

Filed under: FissureMan Products, Product design information — fissureman @ 12:26 pm

Negative comments from prospectors anywhere in the world (no matter how trivial or individual) will always provide “food for thought” to improve current FissureMan product design. While FissureMan products are the best on the market for the money – there is always room for improvement.
 
 
ACCELERATED STRESS TESTING
 
Stress testing is a method of reliability testing used by consumer industry and Military DOD entities to verify a product’s reliability with regard to construction, material, operation and longevity. It can also be referred to as a “Life” test.
The testing and results described below are considered to be more of a stress test than a life test although both identified methods are somewhat interchangeable.
 
Accelerated stress tests can be up to or as long as six months or more and are validated empirical test methods to simulate usable life expectancy of a given item or construction within a compressed window of time. Actual life expectancy limits are applied to various products or components according to the expected use and/or operation they will encounter based on this type of test.
 
The testing written about here addresses FissureMan swing check valve design and is a test performed to generate a valve flapper cycle life expectancy.
 
One cycle is the opening and subsequent closing of the valve flap from closed to full open condition. This action verifies the component construction regarding the physical operation, materials, design, and the adhesion mechanism and/or adhesive materials used to join the *subcomponents of the device together.
(* flap material and construction design along with the flap hinge connection to the valve throat)
 
An initial stress test performed on the FissureMan SANDMAN check valve was conducted for a total duration of 72 hours yielding a calculated 1,296,000 full cycles of the check valve flap.
 
The stated cycle count is based on 5 cycles per second of the valve flap. It should be known the cycle count could have been as high as 10 per second during testing as there was not a stroboscopic timing device available to gain an accurate count of the cycle rate. As a result of this, the cps established is based on the lowest visual estimate of the number of cycles generated per second.
 
To generate a visual cycle count using the valve flap movement as seen in the upcoming video documentation is near impossible to obtain accurately. However, if one rapidly counts from 1 to 5, it takes one second. Doing this while watching the actuator arm during rotation of the main drive gear on the test fixture one can obtain a close estimate of 5 to 8 cycles per second.
 
The test described was applied to the current valve design that is now well over one year old.  (last design update - 12/15/09)
Change made - The backing screen was physically and permanently fused to the valve throat and is no longer attached using an adhesive material.
 
So what does this all mean? It’s pretty simple really - the swing check valve flapper material and hinge connection has been verified to be very robust, durable and will far exceed the cycle duration requirements of standard commercial design specifications.
 
SANDMAN and RINGKING valves will not fail or show signs of wear on the flapper or hinge connection point for well over 1 million full cycles under test conditions that operationally exceed industrial swing check valve reliability requirements.
 
This is significant if you figure the average cycle time for one pump on a SANDMAN or RINGKING to be around 3 to 5 seconds!  Doing some quick math will show that FissureMan swing check valves can be expected to last a very long time.  
 
The above testing is being continued from the initial test point to achieve the total number of cycles needed to obtain catastrophic failure of the flapper components.
 
Periodic updates to this post will be added until catastrophic failure does finally occur. Once completed a short video for review of the test in progress along the various points in time on this thread and the end results of this testing will be made available for review.
 
So stay tuned and check back often!
 
 

7/22/10 - Progress update: 

Testing has made it to 2,592,000 valve cycles - there is no sign of failure in any of the valve components.
 

7/25/10 - Progress update:

Testing for the latest period has completed with 3,888,000 valve cycles - no sign of failure in the valve components.

8/03/10 - Progress update:

Testing for the latest period has 5,184,000 valve cycles completed - Some flap material deformation has been noticed, however, there is no sign of failure in the valve hinge construction or flap attachment materials.
 

8/09/10 - Progress update:

Testing for the latest period has 6,480,000 valve cycles completed - The noted flap material deformation has continued unchanged and there is still no sign of failure in the valve hinge construction or valve flap attachment material.   

8/15/10 - Progress update:

Testing for the latest period has 7,776,000 valve cycles completed - The flap material deformation has continued unchanged. With no sign of failure in the valve hinge construction or valve flap attachment material I am beginning to wonder just how long these valves will last!!   

 

8/21/10 - Progress update:

Testing for the latest period has 9,072,000 valve cycles completed - The flap material deformation has continued unchanged. With no sign of failure in the valve hinge construction or valve flap attachment material. If the total cycle count wasn’t so large it might be boring! :{)   

 

8/27/10 - Progress update:

Testing for the latest period has 10,368,000 valve cycles completed - The flap material deformation has continued unchanged. With no sign of failure in the valve hinge construction or valve flap attachment material. Would anybody care to guess how long this will take? 

 

9/02/10 - Progress update:

Testing for the latest period has 11,664,000 valve cycles completed - The flap material deformation has continued unchanged. Still no sign of failure in the valve hinge construction or valve flap attachment material. 

9/07/10 - Progress update:

Testing for the latest period has 12,960,000 valve cycles completed - The flap material deformation has continued unchanged. Still no sign of failure in the valve hinge construction or valve flap attachment material.   - Yawn! :{O  

    For additional definition to help understand the above testing method better: http://www.weibull.com/hotwire/issue18/hottopics18.htm
 
See what is typically expected in a Swing Check Valve design specification:
 
  http://www.fmglobal.com/assets/pdf/fmapprovals/1210.pdf   
 
       
     

                          

        

 

 

 

June 7, 2010

SLIP OR THREADED NOZZLES

Filed under: Product design information — fissureman @ 3:20 pm

                                                                         TO SLIP OR NOT TO SLIP CONNECT
                                                                   That is the question!
 
There is one particularly vociferous competitor out there that likes to ping on all the other manufacturers of hand dredges (oh yes! – it’s the same one that has been after FissureMan products since day one). He always seems to have some sort of negative comment or attitude to convey on his listings and/or e-store “blog” about other hand dredge manufacturers.
One of these (many) comments is that “friction fit” or slip connectors on hand dredges are real bad for some reason. To paraphrase his statement:
 

The PSP uses a friction fit nozzle. This type of nozzle is used to keep cost down, as using threaded fittings more than double the cost of the nozzles. Nozzles that rely on friction alone to hold them on can and do come off at the most inconvenient time. Plus if sand or grit gets trapped between the mating surfaces, then friction fit type of nozzles can be a bear to take off.
 

This is directed at the nozzle connections used on the FissureMan PickerStick Plus hand dredge.
 

Firstly – to be clear – the slip fittings used on the PickerStick nozzles cost (with tax) - $.95 each. The larger 1” male threaded fitting that could be used will cost (with tax) $.75 each.  I really don’t see how the cost could be “double” for a threaded nozzle fitting in this case – do you?                       You will always get more product for less cost with FissureMan products!

UPDATE 6/30/10: - The fittings for the PickerStick plus are 1 1/4″ diameter slip to 1/2″ / 3/4″ & 1″ slip. These fittings cost more than any narrow 1″ threaded connections as used on the  (sic) “original” gold sucker. If the infamous Ddog had any idea at all about what he writes, he might just have a case and be semi-dangerous but instead he gets defensive and likes to claim I am “shoveling bull”….   
 I may not get the best price on all my raw products but I do have all the facts correct before I write anything!

What this writer finds most riduculous in his statement is not whether a threaded connection is better or less costly but rather the audacity of this individual to state such misdirecting information about “friction fit” nozzles and all the while he sells the following with his “prize” hand dredge package deal:
 

                                             2”  “Super Sucker” “friction fit” nozzle adapter….   

cropped-competitor-slip-connect.jpg

It seems that product construction that’s good for the goose should not be  good for the gander…this does seem a little one sided doesn’t it?

As to a product that will get sand stuck inside and cause mechanical binding –
 
The following exerpt is not this writers words but rather paraphrased from another prospecting site relating to first hand knowledge and experience of a prospector who actually owns and commented on an “original” gold sucker  as provided by this same competitor:
 

“The smaller 1 ¼-inch model is not for large volume use….  It can tend to get some fine sand between the housing and the pump shaft, causing binding/scraping. “ 
 
 
To sum up this blog entry with some technical information - if you don’t want something to bind with sand  - wipe or rinse both mating surfaces off before you put them back together. Using just this simple common sense approach you will get away from 99% of all the concern.
      

 

June 5, 2010

Do you care about quality workmanship?

Filed under: Quality Workmanship — fissureman @ 4:36 pm

Maybe not - but FissureMan does!

FissureMan Online products are consistantly produced with the highest attention to detail - no matter how small.  One of the biggest concerns is to never provide any schlok products for sale as can be found elswhere on the Internet, EBay or even with some home brewed equipment. While not naming names or singling out any one manufacturer, the following are but three catagories of “quality” that lacks detail orientation:

- Barcodes and price tags left on the product

- Rough cut “so called quality” workmanship

- Ink pipe markings left on constructed product

The following are example images of these, less than quality oriented, attributes. You will have to pardon the somewhat blurry look of the images as they are expanded crops of the original picture. However, even being slightly blurry they will convey the concern effectively.

 cropped-finishing-sluice-fitting-marking.jpg cropped-finishing-sluice-marking.jpg cropped-gns-bucket-marking.jpg cropped-wide-copy-cap-marking.jpg

cropped-wide-eye-copy-marking.jpg cropped-gns-nozzle-marking.jpg cropped-wide-eye-copy-body-marking.jpg cropped-gns-fitting-marking.jpg

Many of these examples are readily seen without any alteration of the picture, however, if you need to, take any of the original posted pictures and zoom in for a close review - they are readily seen. Some may be harder to distinguish than others as the position of the product is set up such that the marking or tags are placed either almost out of site or completely hidden from view with only a clean side showing.

These picture “oversights” may be explained away by a manufacturer as something found only on the picture descriptions but never sent to a customer. However, it seems quite apparent to this writer that if the manufacturer can’t or won’t remove tags and markings for even the a simple picture used to advertise then what would make one think that they would be removed from the final product that is purchased.

These few examples may seem trivial and completely acceptable by some purchasers but they still shown a lack of true concern to provide the absolute best quality workmanship for the buck spent by you.

 

May 31, 2010

IDEAS and SUGGESTIONS

Filed under: Product design information — fissureman @ 12:47 pm

IDEAS WANTED, NEEDED AND APPRECIATED

FissureMan Online currently has some of the most advanced hand dredges and products on the market for gold prospecting and metal detecting enthusiasts around the world. 


However, I really don’t consider myself or all my ideas as the “be all - end all” for this line of products.
 
FissureMan Online strives to provide only the best quality and innovative products for fair and reasonable cost.
 
It will be very much appreciated having you share your ideas and suggestions concerning any part of the form, fit, feel, construction, function, advertising, shipping or anything else you as the reader can come up with that will help improve FissureMan Online products.
 
“Appreciated”? You bet! I am not going to just take and use your suggestions and ideas - say “thank you” and then walk away. Oh no! – that would not help you in the slightest would it?
 
Here is what I will do if you provide a suggestion or idea that is found acceptable and ultimately used.
 
Any suggestion or idea that helps to improve current products or provide an additional usable and saleable product suitable for listing on FissureMan Online will be:
 
1 – Recognized with the usual “Thank you”.

2 - Accepted product improvement suggestions used to improve a FissureMan product will be identified on the FissureMan Online website as your idea right on the page it is listed.

3 – For your accepted and incorporated suggestion you will be given a 10% discount on the product cost for your next FissureMan Online purchase.
 

4 – If your suggestion provides a new product that is found to be accepted, viable and listed on the FissureMan Online website you will be sent a completed unit absolutely free once production begins.
 
There are a couple of ways to submit your suggestions or ideas:
 
1 – Post them here, I monitor this blog and will see your post and respond.
2 – Send an email of your idea or suggestion for improvement to fissureman@goldsucker.com .
 
 

What guarantee is there that I will do as I say?
 

Well the first guarantee is: “my word is my bond”.
The second and foremost guarantee is - Without customers I would have no business. To treat you wrong is to treat me wrong – I never treat myself wrong!
 
So at the very least you will be thanked for your submission and at the opposite end of this scale you might have your idea professionally constructed and sent to you for free. 
 
 
FissureMan

May 30, 2010

Prospector and Engineer

Filed under: FissureMan Products, Product design information — fissureman @ 6:31 pm

Prospector and Engineer
 

Prospector - someone who explores an area for mineral deposits
 
Engineer - a person who uses scientific knowledge to solve practical problems
 
 

I have done my fair share of prospecting – at least what I consider to be enough time spent to know, understand and perform the needed functions in the quest to find gold and other valuables both in the water and on dry land.


 

I was also an Engineer for the majority of my working life (23 years) when I was holding down what would be considered a regular job to produce an income for my family.  No - I was not driving a train but rather designing, developing, testing and verifying product quality in coordination with a whole host of other individuals in various manufacturing disciplines. I had to have a deep familiarity with all engineering disciplines to perform my working duties successfully both on paper, while using my hands and coordinating the efforts of other individuals.


These various disciplines include Hydraulics, Mechanics, Electronics, Pneumatics. Machining, Quality & Metrology.
 
This background experience provides the basis for what I do now to provide some additional income for my current family and myself. I design, manufacture, distribute for sale a line of superior hand dredges and assorted prospecting equipment for individuals and concerns around the world.
 
Here are a couple of questions to ponder and reply on if you care to:
 
When buying prospecting related equipment:
 

Is it important that the person or outfit one buys equipment from actually be actively prospecting?  Why?


Is it important that an individual or outfit actually be able to design and build prospecting equipment using sound background knowledge of the subject along with demonstrated mechanical ability while not actively prospecting?  Why?

The “Challenge”

Filed under: FissureMan Products, Product design information — fissureman @ 1:37 pm

Perhaps you have read this statement on another blog site:
 
Anyone interested in a hand dredge challenge? If you are, let me know.  You bring your hand dredge, be it a  Gold-n-Sand, or one of the copy cats like SMB_PROSPECTING HAND DREDGE or  SM_PROSPECTING HAND DREDGE; or a Keene; or one from Jobe or any other hand dredge; and I will bring mine. The point of the challenge will be to determine which hand dredge can move the most material.”
 
While one can say what they want on their own blog site, the operator who posted such a statement is obviously misled and attempting to mislead others. He has been very unhappy with the popularity of both FissureMan SANDMAN (SM & SMB) and Gold-N-Sand hose and bucket collection systems since they hit the market.
In particular he attacks FissureMan products like a lizard trying to eat a bug too big to fit in its mouth – in that analogy the lizard chokes on his intended victim and still doesn’t get a meal while the bug gets back up and continues about its business. Lizards aren’t too smart in this respect.
 
This is not the first time he has tried and failed to eat this bug - he has been after FissureMan products ever since day one when FissureMan Online got started and gave him his first real taste of competition with a superior hand dredge. Before that he had the majority of the hand dredge market happily to himself.
 
Neither the SANDMAN nor Gold-N-Sand bucket and hose systems are copycats of one-another. Both designs came onto the market at the same time - within the same actual week. This is a case of two smart people coming up with the same idea and releasing a product at the same time – “serendipity” is a word that comes to mind for me.
Both work on the same principle and may even appear on the surface to be the same but they are physically much different when it comes to many of the operating and mechanical attributes.
In actual fact they are both good machines for the intended purpose. That purpose is to collect material as efficiently as possible and with less operator fatigue – this is as close to “copycat” as they actually get.
 
Both the valve and piston technologies used are the first two greatest departures. The pump body is also different in that the SMS is physically bigger in length and diameter – if either were a copy of the other they would be the same in all respects  - not just that they are both black in color and use a 2 gallon bucket with a hose.
 
Ask yourself this question  - How could a copy have been accomplished of such an advanced hand dredge design show up on the market within the same 7-day period?  Neither myself nor Red (owner of GOLD-N-SAND) had any idea of the others work until we both placed our concepts on the open marketplace. Nobody (not even me) can design and build a machine from scratch such as these that quickly and have it work as well as the other within the same week unless both were already in design and near completion at the same time. 
 
What you have here are two smart people coming up with similar concepts for a manual suction dredge that will far outpace any swizzle stick like the so called “original goldsucker” or any of its oversized redesigns intended to compete with an advanced bucket and hose collection system.
 
Any “competition” suggested to try and see who can move the most dirt would hold no true value. Each operator’s physical ability using their respective hand dredge and the material available to collect will vary wildly. This is just another competitor attempt to bolster an overinflated product ego and hopefully show some sort of continued usefulness for such an overrated and obviously dying breed of outdated single action hand dredge equipment.

Update: 6/28/10

It seems that the competitor I mentioned in this post is trying to eat something else too big to fit his mouth again! He has attempted to refute what I stated about the inception timing and release of the two different versions of the bucket and hose hand dredge. Along with other blather he states the following on his attack blog on 6/24/10 concerning when the two H+B hand dredges came to fruition: 

“Let’s see, from Apr-17-08 to Oct-05-08 is only a week. NO, it is 12 days short of 6 months!!!!!”

If he had done any sort of accurate and meaningful research he would have seen that the first GOLD-N-SAND B+H system sold by that manufacturer on EBay was on 4/10/08 not 4/17/08 and that the first SANDMAN was sold on 5/5/08. The attacking competitor appears to not wish the reader of these posts to recognize the true fact that the SANDMAN H+B system was first sold as an attachment and not as a full hand dredge system. His posting attributes the SMB System as the first B+H system sold on 10/6/08 - WRONG!!!

Additionally, the date of sale of an item does not mean that was the first date of product concept inception. One cannot relate the first sale made of an item to the date that it was first conceived and built for sale. This is just another attempt by this “competitor” to muddy and roil the waters in a lame attempt to steer potential sales away from FissureMan Online with more misleading and erroneous information.  The best one can do to compare when two items of similar nature may have come to market would be the date they were first LISTED for sale not the first DATE of sale for a given product. I used to the first listing dates of sale for both items not the first date of sale in my statement above referencing the 7 day period stated.

May 23, 2010

Hand dredge physics of operation Part 3

Filed under: Product design information — fissureman @ 3:31 pm

PHYSICS OF PRESSURE  It is suggested that the reader review all the scientific explanation (provided in layman’s terms) for pressure v/s area on the supplied web site at the bottom of this page. The information is very easy reading and if needed will help one understand some of the information presented on this page.   There are two physical conditions that any pressure will exist as - POSITIVE (High) Pressure and NEGATIVE (Low) Pressure which are inversely proportional to one another and will act in concert to one another. There are three types of “pressure” - 

static pressure   -   ram pressure   -   dynamic pressure All three exist within a hydraulic mechanism Static pressure decreases when the velocity increases -  

Static pressure is the pressure of a fluid with no movement.  “In the initial pipe configuration (of the linked interactive example) the static pressure on the right side is higher than the static pressure on the left. This does not mean the fluid is flowing from a lower pressure towards a higher pressure, since the total pressure is the same at every point.”  

Ram pressure increases when the velocity increases - This is the pressure referenced on this page and to explain the statements made previously regarding superior suction pressure/force at a nozzle orifice.  Static pressure should not be confused with ram pressure, which is the pressure felt by an object because it is moving relative to the fluid. Basically, the fluid is ramming into the moving object, or vice versa.” A simplistic way of describing this action would be that Ram Pressure is the force transmitted to the water by a piston in motion that actually moves the gravel and sand. 

Dynamic pressure corresponds to the movement of the fluid - through the pipe, and is simply another name for the velocity terms in Bernoulli’s Equation. This form of pressure is also referenced within this page text as velocity. Since the pressure difference between two points creates the force that accelerates the fluid, we see that increasing the pressure difference increases the fluid velocity difference.” 

The following site link will help explain the basics of hydraulic theory for the reader and was used as an information source for some of the presented information on this page. Bernoulli’s Principle: http://home.earthlink.net/~mmc1919/venturi.html 

Hand dredge physics of operation Part 2

Filed under: Product design information — fissureman @ 3:18 pm

PRESSURE GRADIANT FORCE
The change in pressure measured across a given distance due to exerted force is called a “pressure gradient”.
 The pressure gradient results in a net force that is directed from high to low pressure and this force is called the “pressure gradient force”.
 The resultant movement of material (sand and gravel) within the water provided by Ram Pressure is the result of the induced changes to the internal and external pressures of a pressure gradient during manual suction dredge operation and by it’s design.
 A pressure gradient is high pressure acting on and in concert with low pressure.
 A manual hand dredge is a “suction” device using an open hydraulic system and is a negative pressure system. It is not the positive pressure that lessens with the use a large piston diameter. The negative or low pressure is what lessens, and in the case of a negatively developed pressure – less is actually more since the positive pressure on the opposite side of a pressure gradient transition point (the nozzle orifice) will rise equally and inversely to the negative pressure that is developed by the piston.
 With these actual facts, the following occurs – as pressure (negative) drops with a piston of greater diameter, the positive pressure rises inversely at the transition point (the nozzle orifice). The smaller orifice diameter of the nozzle additionally constricts the fluid flow and thus the action of Ram Pressure is amplified on the material being suctioned at the orifice within the water column.
 
The greater the negative pressure on the face of the larger piston of a manual suction dredge the higher the inverse positive pressure will be at the nozzle orifice from the developed pressure gradient.  This inverse pressure gradient force induces Ram Pressure to act upon the gravel and sand entrained within the water during operation. 

Hand dredge physics of operation Part 1

Filed under: Product design information — fissureman @ 3:08 pm

A  LITTLE THEORY
AND
A LOT OF SUPPORT FACTS
This article will contain subject matter regarding the function and design of manual suction dredge devices. Since there is not much available in this area of endevour, the next text article will present credible and useful information concerning some of the theory of hydraulics technology. It will also provide some functional understanding of the physics and processes as they apply to a manual suction dredge and nozzle design.     
 
Nozzle Definition 
“A nozzle is often a pipe or tube of varying cross sectional area, and it can be used to direct or modify the flow of a fluid (liquid or gas).
 
Nozzles are frequently used to control the rate of flow, speed, direction, mass, and/or the pressure of the stream that emerges from them.
 
http://en.wikipedia.org/wiki/Nozzle
                                                                                                        
Pascal’s law -   päskälz´ [for Blaise Pascal], states that pressure applied to a confined fluid at any point is transmitted undiminished throughout the fluid in all directions and acts upon every part of the confining vessel at right angles to its interior surfaces and equally upon equal areas.
Practical applications of this law are seen in all hydraulic mechanisms and for this explanation - Manual Suction Dredges.
  
When speaking of the suction nozzle diameter and flow-through capacity of said nozzle it should be understood that nozzle flow-through capacity is a reference to the amount of desirable material collected and then held within a chamber prior to, during and after collection. 
 
When the piston of a manual suction dredge is compressed or extended the hydraulic force of this mechanical action is transferred to a liquid and used to provide a suction and/or expulsion action. In the case of a manual suction dredge this liquid will be water containing liquefied solids being drawn into the piston or other collection assembly on the suction stroke and then the water (possibly the solids as well) being pushed out during the reverse expulsion stroke through the nozzle.
 
A hydraulic piston converts mechanical energy of motion into the hydraulic energy of ram pressure and with the velocity flow created at the nozzle orifice converts the hydraulic energy into the mechanical energy of material flow during suction or expulsion.
 
With this in mind, the ratio of the piston diameter to nozzle diameter is of great importance to the overall effective nozzle suction force, ease of operation and collection ability of a manual suction dredge.
 
For instance: Take a piston diameter of 1” and a nozzle diameter of 1” with a force applied to the piston equal to 1 (for discussion purposes). This force may be varied depending on the energy applied at the handle but will make no difference to the final outcome of the piston to nozzle ratio. However, it will affect how fast the material will flow through the nozzle on each stroke of the handle.  A one inch diameter piston mated to a one inch nozzle will be very easy to draw on with a minor vacuum created but would have very low ram pressure since the ratio of 1:1 would be all that is achieved. One thing that increases the flow  velocity for this ratio is the application of additional force applied to the piston by the operator - more work….. Alternatively, if the piston diameter is increased and the nozzle diameter stays the same, then the subsequent ram pressure and velocity will be increased at the nozzle orifice with no appreciable change required to the force applied.
 
To determine a ratio for this action, a simple calculation would be:    1 / 1 x 1 = 1:1 or the piston diameter divided by the nozzle diameter multiplied by the energy (force) applied equals the ratio of ram pressure to flow converted at the nozzle orifice.
 
Now with a little math applied and a set of parameters set to various size nozzle and piston diameters of  various manual suction dredge sizes, one can extrapolate a relative ram pressure and velocity strength of the material flow through at the open end (orifice) of the nozzle.
  
Piston Diameter /  Nozzle Diameter x Force = Pressure Ratio       
  1.250”             .500”                   1              2.5 : 1
  1.250”             .750”                   1              1.7 : 1
  1.250”            1.000”                  1              1.3 : 1
   2.000”             .500”                   1              4.0 : 1
   3.000”           2.000”                   1              1.5 : 1
 
What the chart above shows is that the higher the piston to nozzle ratio is, the better and faster material will flow through the nozzle orifice for a given force exerted – In other words, the mechanical advantage of the larger piston diameter compared to the smaller nozzle diameter provides more ram pressure and material velocity at the nozzle opening.
This will equate to - less work for the operator due to the increased ram pressure and velocity  generated during suction collection to move the entrained material!
 
 
The following site link will help explain the basics of hydraulic theory for the reader and was used as an information source for some of the presented information on this page.
PRINCIPLES OF HYDRAULIC PRESSURE: http://www.tpub.com/content/engine/14037/css/14037_67.htm

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