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scaylabs 01-11-2013 07:23 PM

Uruguayan Grill, a manual
 
Just spent some time translating this. Most of it will seem basic to most of you but hopefully someone will find some useful information.

Uruguayan and Argentinian grilling styles differ mostly on the fact that you will never see an asado being made using charcoal in Uruguay, always firewood. Of course, it's mostly a matter of tradition, except for the small amount of smokiness that can be transferred to the meat (yum).

A small note on the use of the word parrillero throughout the document: in uruguayan spanish a grill, as in cooking surface, is a parrilla. A grill, as in the whole structure that holds the cooking surface, hood, etc, is called a parrillero (not so in Argentinean spanish, where the parrillero is the cook using the grill). I couldn't find an equivalent word in english to translate it, so I kept using parrillero throughout.

Images are from a scan of the original document, which can be found in pdf form here (in spanish): parrillerofamiliar.pdf

Here it goes:

Originally published in the 1988 Almanaque Anual del Banco de Seguros del Estado (Uruguay)

By Arq. Diego C. Venturini

The delicious practice of grilling and savoring meat ďon the coalsĒ exists within our people since yore.

Throughout time said practice has been perfected and from the old parrilla criolla laid on the ground, different improvements have been made, looking in them to achieve more comfort and efficiency.

The main objectives, when building a parrillero are:

* firewood economy
* time saving
* comfortable working areas
* easy coal production
* fast smoke exhaust

We are focusing today on family parrilleros, of sporadic use. Commercial parrilleros, of continuous use, have characteristics and requirements that need to be studied separately.

While we will be studying the parrillero itself, itís important to consider several elements that can complement it. This could be an adequate exterior space, a paved area where to have a table and chairs, a nearby sink for food preparation; protection from the sun or rain that can be obtained through different plants, pergolas, awnings, metal roofs, concrete slab, etc.
It should be located if possible sheltered from air currents.

We will analyse the following components of the parrillero:

I. Firewood holder
II. Grill
III. Coal surface
IV. Hood and chimney

I. Firewood holder

Itís a metallic structure where the firewood is burned. Itís function is to facilitate the production of hot coals.

Itís usually made with iron round stock of diameters varying between 10mm and 19mm joined by welding.
Because itís exposed to direct fire, it will suffer the process of corrosion. Thus, it is convenient to make it of easy replacement. (Fig. 1)
To have correct combustion and to easily obtain coal, the distance from the base of the holder to the floor surface should be between 15 to 20cm. (Fig. 2)

To have an even easier access to the coals a version of the holder can be used which substitutes the front legs for brackets secured to the wall. The higher this brackets are, the less force they will have to endure.
Since replacing these brackets might be complicated, itís best if the holderís weight is supported by the rear legs on the floor. (Fig. 3)

http://img.photobucket.com/albums/v6...ps1c0f07d2.jpg

II- Grill

Itís the metallic surface where food is laid to cook.
Itís quite common to see it made out of an iron frame (angle iron or thick round stock) to which round stock of 6 to 8mm is welded. (Fig. 4)

http://img.photobucket.com/albums/v6...psa8d79dde.jpg

Distance between pieces of round stock should be so that they keep food from falling but at the same time letting the heat from the coals through. Said distance can be increased in areas of the grill or a uniform distance can be used through the length of the grill. In this last case the separation between the pieces of round stock shall be of 1.5cm.

The width of the grill, to keep smoke from coming out of the parrillero opening, shall be limited by it's depth, measured to the inside edge of the lintel. (Fig. 5)

http://img.photobucket.com/albums/v6...ps9fe3f404.jpg

To graduate the amount of heat that reaches the food itís possible to give the grill some mobility. This is possible through a pivoting axis which allows for varying angles, which will regulate the distances to the burning wood holder and the coals. (Fig. 9)

http://img.photobucket.com/albums/v6...ps1fbf8d4b.jpg

For an even greater mobility several pivots can be installed at different heights. If only one axis is to be used, then it should be located at the second row of bricks (about 12cm from the surface).

...continued

scaylabs 01-11-2013 07:25 PM

Re: Uruguayan Grill, a manual
 
Several methods exist to raise the grill.
Among the most common is the pulley and spool for steel cable (Fig. 6), or pulley and chain fastened to a hook on the wall. (Fig. 7)
Another method is to have the steel cable rolled on an axle which ends on a handle with lock to keep itís position. (Fig. 8)

http://img.photobucket.com/albums/v6...ps3a1626fa.jpg

III. Coal surface

This is divided in two distinct areas with different characteristics:

*The fire area: which will endure the highest temperatures and support coals and ashes.
*The cooking area: which has lower temperatures but supports, besides coals and ashes, also the fat rendered from the cooking food.

The materials most used to surface both areas are the common bricks, and refractory bricks. Both materials have advantages and inconveniences. To choose correctly itís important to know their properties and behaviors.

Refractory brick has smooth faces, which diminishes adherence to mortar, resists high temperatures and abrasion, itís a poor thermal insulator and itís more expensive.

Common brick has rough faces, it handles high heat poorly which greatly reduces itís life expectancy, doesnít resist abrasion very well (deteriorates when brushed to clean the surface), itís a good thermal insulator and has a lower cost. (Fig. 10)

http://img.photobucket.com/albums/v6...ps2474cd63.jpg

If we choose to make our surface out of common brick itís good to know that, throughout time, the bricks closer to the fire (and itís mortar) will slowly disintegrate, so itís convenient to plan on their eventual replacement.

Refractory bricks, because of their low thermal insulation coefficient, should be set on a layer of sand and salt in a 20 liters to 1 kg proportion.

In both cases a mortar resistant to high temperatures should be used, which can be based on aluminum silicates or sodium silicates, or ground refractory bricks and refractory clay.


IV. Hood and chimneys.

Itís objective is to capture and exhaust the smokes generated within the parrillero.

There are two distinctive smokes. The smoke produced in the fire zone, is light and high temperature, while the smoke produced in the cooking zone is of lower temperature but of higher density as it contains fatty vapors.

The location of the fire in relation to the exhaust duct plays an important role in the smoke exhaust. When the duct is on top of the fire, a high temperature and high speed current is produced, making access to the duct harder for the heavier smokes. (Fig. 11)

http://img.photobucket.com/albums/v6...ps3415e31e.jpg

Materials most commonly used for the smoke hood are ceramics, concrete and sheet metal.

The hood should be shaped appropriately (funnel) so that if facilitates the exhaust of the smoke. The closer the angle of itís walls are to horizontal, the harder it will be for the smoke to channel through and the higher the amount of fat that will remain on itís walls.

Regarding the height of the hood, the shorter the distance to the coal surface, the smaller the probability of smoke coming out the parrilla opening. On the other hand, we should ensure the visibility of the fire and the food for the cook. (Fig. 12)

http://img.photobucket.com/albums/v6...ps5d5c9eff.jpg

To aid in the smoke exhaust, the interior surfaces of the hood must be as smooth as possible. On hoods made of staggered bricks you should make sure to cut them or fill in the holes with cement.
On hoods made of concrete, the form can be made out of planed wood to ensure a smooth finish.

The construction and operation of the chimney is similar to a wood burning fireplace. The basic mechanism of a chimney is based on the difference of pressure between the interior air and exterior air. The natural draw is produced by the ascending movement of air when it is heated. This rise in temperature makes it lighter and therefore it rises. For a same duct cross section, draw will increase if the difference in weight between interior and exterior air is greater, or if the height of the chimney is increased, or if the friction on the walls of the chimney is decreased.

continues...

scaylabs 01-11-2013 07:26 PM

Re: Uruguayan Grill, a manual
 
Pressure differential. To maintain a good weight difference between interior and exterior air it is necessary for smoke to arrive hot to the chimney exit. For this the chimney walls need to have good thermal insulation. Itís important that the chimney walls are free of cracks or holes through which the hot air can escape, otherwise the effect is similar to smoking a cigarette with holes on the sides. (Fig. 13)

http://img.photobucket.com/albums/v6...ps8c74b260.jpg

The height of the chimney has to be such that the exit of the smoke is unimpeded by nearby obstacles (structures, trees, etc). The higher the chimney the greater the volume of moving air which increases the chimney draw. (Fig. 14)

http://img.photobucket.com/albums/v6...ps113b4ea3.jpg

Friction. Smoke rises in a spiral inside the duct. This means that the area in the corners of a square or rectangular duct is not utilized. Further, in those corners is common for swirls to form, which hinder a good draw. In these circumstances draw can be improved by rounding off the interior angles of the duct. As the hood, the smoke duct shall be free of obstacles, having an internal surface as smooth as possible. (Fig. 15)

http://img.photobucket.com/albums/v6...psed65659f.jpg

Cross section. To calculate the cross section of the duct we follow similar guidelines as used for wood burning fireplaces. For these itís recommended a duct area 8 to 10% of the fireplace opening, for chimneys 10 meter high (measured from the joint with the hood to the chimney cap). In the case of parrilleros, being that the smoke is thicker and the chimney height is generally smaller, draft is increased by using a larger cross section. For low height chimneys, the recommended duct area will be 10 to 15% of the parrillero opening.

The usage of a chimney cap will protect the duct from descending air currents. (Fig. 16)

http://img.photobucket.com/albums/v6...ps59b5ff79.jpg

This are some of the subjects to consider when building a family parrillero.

scaylabs 01-11-2013 07:28 PM

Re: Uruguayan Grill, a manual
 
http://img.photobucket.com/albums/v6...ps967756db.jpg

Laurentius 01-11-2013 10:38 PM

Re: Uruguayan Grill, a manual
 
Thank you that was great and well done, it gives me something to look forward to.

rosstaylor2440 02-14-2013 08:14 PM

Re: Uruguayan Grill, a manual
 
Well those are the awesome designs! thanks for sharing with us!

bing 02-24-2013 12:37 PM

Re: Uruguayan Grill, a manual
 
want to build this grill. i do not see all dimensions ( hood). can somebody put all dimension in picture? also i wonder to made the behind wall sloping ( like in thread Argentinian Parrilla wood/charcoal grill)?
that grill will be indoor, in the garden house, so smoke is not wanted. what else to do for non-smoking one??

bing 02-24-2013 12:58 PM

Re: Uruguayan Grill, a manual
 
want to build the second one, and make some changes on back wall.
http://i48.tinypic.com/2v9rbiu.jpg
http://i45.tinypic.com/10gw8zn.jpg


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