Insights

 

How to explain and defend

the choice of our

raised access floor?

 

 

 

The raised access floor is already well known and largely diffused worldwide, obviously following different levels of knowledge by the users. 

 

to say always the truth not envisaging the impossible

 

to explain the differences and illustrate the rules

 

Every country has his own national rules and its own producers who, sometime, arise possible technical problems, emphasising too much their own supposed quality or the defects given by others… 

 

JVP have chosen to certify all its products as per the most diffused and respected International Rules & Standards.

 

JVP offer to everybody should be interested a wide range of analysis, observations and clarifications about the actual Standards and technical matters more often discussed.

 

 

the JVP 4x4 raised access floor, reason for a choice 

quadrupede

 

 

Space saving.

The expected life span of a building is generating costs like maintenance and management that sometimes are much bigger than the initial cost of construction( heating and cooling, power distribution and lighting are clear example).
The use of a raised access floor with self bearing gravity laid panels such as the JVP 4x4 allow the reduction of the total height of the building. In fact thanks to the combination of reduced space required for the MEP (Mechanical, Electric Plumber)service’s systems and the stringer-less support structure and the slim robust construction of our panels significantly reduces the void space to the point that it contributes greatly terms of savings in build cost. 

 

Cost saving.

 The use of raised access floor self bearing gravity laid bare panels such as the JVP 4x4 will shorten the construction programme because it removes the requirement for a floor screed which is an unwanted “wet trade”. In fact due to its robust construction it can be installed just after the external cladding, and used as a working platform particularly considering that for all void heights of below 700mm it can be used without stringers which avoids any delay to the service’s system and provides a level surface for the removable or dry wall and the movement of the wheeled internal scaffolding towers.

An important aspect of the cost saving is the possibility to use loose lay floor-covering at second stage fit-out, reducing early financial burden and increasing the flexibility of customer choice and use greatly reducing the potential for wastage.

The construction of a system that will suit the requirements of the service’s structural grid layout combined with the application of a covering finish that will satisfy the need of good aesthetic content; will clearly save considerable wastage, and time. 

 

Time saving. 

The use of a raised access floor as a working platform during the construction period will reduce the time taken to install MEP (Mechanical, Electric Plumber) service’s components and will speed up the fitting out of interior of the building. This is only possible if the full system of the raised access floor can bear the function of working platform. The JVP floor is made with high performance cores enhanced by fully encasing with a hot dipped galvanized steel envelope fabricated with a special welted pressing joint at the top edge of each panel. This type of fabrication results in a strong robust surface upon installation. The use of fully adjustable pedestals provided with substantial locking nuts enhances the strength and stability of the system to handle the rigorous conditions of the building site.

The previously mentioned reduction of time for interior fit out installation added to the ease of circulation for pedestrians and the convenience for storage of materials on top of the raised access floor provides remarkable saving in time and money on construction, leaving a finished building ready for occupancy earlier than other type of construction techniques. 

 

Maintenance saving.

The use of a raised access floor naturally creates the ability to access and replace the MEP (Mechanical, Electric Plumber) service’s system in the floor void whilst at the same time conveniently maintain, repair/refurbish the existing system.

A wide range of gravity lay coverings are available to be applied immediately before the incoming tenant takes occupation of the building. In addition to the tried and tested finishes of carpet tile, rubber, vinyl and linoleum, we have developed an even wider exclusive range of finishes such as; ceramic tiles, marble, granite, timber parquet all gravity lay without any limitation in size, grid and design.

The tenant client will be able to choose the quality and the type of coverings for its new premises, just prior to occupation completely alleviating the risk of damaging these finishes during the main construction. Moreover, if in the future there is a need to change the image of the company; then the cost of changing the covering will be limited to the cost of a new covering only. 

 

 

the load bearing capacity, analising the standards

portate meccaniche

 

 

Load bearing capacity: standards EN 12825 & PSA MOB, introductory note.

  

The EN 12825 Standard also defines the load bearing capacity classification of raised access floor systems.

 

The load baring capacity of a raised access floor is a most important parameter for the future use of the system and should be related to the type of activity managed within the building where it is installed.

 

Nevertheless consideration for use of most commercial working space needs a balance between technical performance and consequent costs.

In fact the ergonomics of a building is directly related to the proper use of each single component’s performance criteria.

 

Within EN 12825 the use of a specific class of load bearing capacity for the final application is not clearly stated while within the more consolidated specification format K41 based on PSA/MOB from the United Kingdom the general indication of load bearing capacity versus environment use is considered.

 

Specifically K41 gives details of the concentrated loads applicable on each raised access floor system to produce a maximum elastic deflection that the system has to sustain for general commercial use: Considering the maximum allowable deflection (elastic temporary deformation of the system components under load) of 2.50 mm K41 is giving an idea of the type of application suitable for the load requirements.

 

Within K41 there are four classes b(Grades) of load bearing capacity with their final use indications:

 

Light Grade

Standard application for office space equipped with filing cabinets, standard office equipment with average density of occupancy, without the need of application of heavy machinery and or archive storage, generally defined as normal use private office space without heavy volume of pedestrian foot traffic.

1.50 kN concentrated load (25 mm square) with deflection below 2.50mm

The above data corresponds with Class 1 and 2 of EN 12825

 

Medium Grade

Standard application for commercial office space equipped with filing cabinets, general office equipment with average density of occupancy including flexibility for the future changes in application. Normally used for private and public commercial offices, Banks, Retail Shops, Libraries, etc.

Generally defined as heavy volume foot traffic circulation and medium machinery equipment and/or heavy filing/archive storage.

3.00 kN concentrated load (25 mm square) with deflection below 2.50mm

The above data corresponds with Class 3 and 4 of EN 12825

 

Heavy Grade

Specific use of technical spaces like electrical cabinet, server room, telephone exchanger cabinets, industrial laboratory, light industrial production.

Generally defined as space where the loading of machinery is and will be higher than general offices.

4.50 kN concentrated load (25 mm square) with deflection below 2.50mm

The above data do corresponds with Class 5 and 6 of EN 12825

 

Extra Heavy Grade

Normally used for heavy plant rooms and or particularly heavy machinery and or extreme heavy rolling loads (car showrooms).

EN 12825 does not have a classification corresponding with Extra Heavy Grade. 

 

A further element considered by the K41 is Uniformly Distributed Load (UDL) capacity which is not mentioned or considered by EN 12825.

 

The UDL it is not an important element to qualify a raised access floor performance, because the limit of the performance of a raised access floor is the performance of the concrete slab of the building, which is normally limited to the UDL range of 2 to 8 kN per square metre. This value is considerably lower than the load bearing capacity of a raised access floor light grade performance.

 

Following an analysis of the considerations of EN 12825 we underline the maximum and minimum limit of performance:

 

According to EN 12825 the best achievable result of a system is : 6/2/A/1

Failure load class 6, safety factor time 2, deflection class A, size tolerance class 1

 

According to EN 12825 the minimum achievable result of a system is: 1/3/C/2

Failure load class 1, safety factor time 3, deflection class C, size tolerance class 2

 

Article 4.1 – chart of failure load on the weakest point of the system

 

lilmit kN

>4

>6

>8

>9

>10

>12

class

1

2

3

4

5

6

 

The general class of the system is determined by the failure load on the weakest point of the panel and then compared by deflection at the maximum allowed load of each class. 

For example; a failure load of 9.18 kN anywhere on the panel will be classified at class 4, a failure load of 4.82 kN anywhere on the panel will be classified at class 1. To be sufficiently verifiable the test should be done on at least three points of the panel i.e. centre of panel, centre of edge and on the corner diagonal and the higher the declared class the better the performance of the system. 

To omit some of the results or use only the more improved ones gives incomplete information and results that cannot be relied upon!

 

Article 4.2.2 – Safety Factor

 

Safety Factor

2.0

3.0

 

The limit load of each class divided by the safety factor will determine the minimum value in kN that the panel has to sustain on its weakest point with a specific acceptable deflection. 

For example; a failure load of 9 kN of class 4 divided by the safety factor 3 determines a minimum load of 3.0 kN in order to generate a stated limit deflection on the weakest point of the panel. 

To be sufficiently verifiable the test should be done on at least three points of the panel i.e. centre of panel, centre of edge and on the corner diagonal. 

The adopted safety factor can not improve, in any case, the original general class which is linked in principal to the failure load. 

To omit some of the results or use only the more improved ones gives incomplete information and results that cannot be relied upon!

 

Article 4.2.2 - Class of deflection on the weakest point

 

limit mm

2,5

3,0

4,0

class

A

B

C

 

The load limit of each class divided by the safety factor will determine the minimum value in kN that the panel has to sustain on it’s weakest point with a specific acceptable deflection. 

For example: the class of deflection A of a panel of class 4 with a safety factor 3.0 require a minimum load bearing capacity on the weakest point of 3.0 kN with the same load a class B require a maximum deflection of 3,00mm and the class C will allow a deflection of 4,00 mm. To be sufficiently verifiable the test should to be done on at least three points on the panel i.e. centre of panel, centre of edge and on the corner diagonal. 

The higher the deflection, the lower the class of load bearing capacity of the panel, the declaration of class B or C is the clear confirmation of lower performance panels. 

To omit some of the results or use only the more improved ones gives incomplete information and results that cannot be relied upon!

 

Article 4.4 – Dimensional tolerances of the panels +/- in mm

 

Class of tolerances

class 1

class 2

Side dimension

0,2

0,4

Squareness

0,3

0,5

Side straightness

0,3

0,5

Thickness of bare or faced panels

0,3

0,5

Twist

max 0,5

max 0,7

Concavity convexity

max 0,3

max 0,6

Height difference within edge of panels

0,3

0,4

  

The tolerances class determine the dimensional allowed tolerances of thickness, squareness, planarity convexity etc of the panels. 

For example:

Class 1 on the side dimension allows a tolerance of 0.2 mm,

Class 2 on the side dimension allows a tolerance of 0.4 mm.  

The higher is the dimensional tolerance class and more irregular and inconsistent are the panels, the installation of a non consistent product will strongly affect many aspects of the performance of the floor in a negative manner; creating difficulties in accessibility, noise attenuation and safety in use. 

To omit some of the results or use only the more improved ones gives incomplete information and results that cannot be relied upon! 

 

 

the fire, analising the standards  

 

Fire reaction & resistance: standard EN 13501-1 e 13501-2, introductory note.  

 

The European Standard EN 13501 defines the class of materials on their reaction in the case of fire. 

 

This standard is given in two parts:

 

13501-1 fire reaction and smoke emission

 

13501-2 fire resistance and insulation

 

They have been received by the vast majority of the European National Institute of Standardisation, and within a maximum of two years all the member of CEN (Central European Normalisation) will be bound by the new standard with the intention that it is to be the only reference of reaction in case of fire, replacing and cancelling all the previous national standards. 

 

For all the construction elements, raised access floors included, the reaction in the case of fire becomes a very important matter. Our introductory note on this page tries to give a clearer explanation of the considerations beside the National attitude towards fire reaction and resistance. 

 

The EN 13501-1 Standard is focus on fire reaction, evaluation and classification once materials and/or systems are in contact with flames, analyse their contribution to the fire by the single elements as well as the fire loading contribution of the whole system. Special attention is given also to the smoke emission of an element which is in contact with fire (it is commonly known that in the case of most fires toxic smoke claims the first casualties). 

 

The EN 13501-2 Standard is focused on fire resistance, evaluation and classification once material and or systems are involved in a fire. They set out to analyse the capacity of the system to be a fire barrier and/or a thermal insulation barrier. 

 

Both standards classify the performance of a material and/or system on their reaction in case of fire, the test procedure and the classification method are part of different European Standards related to this main one and the test report and the Classification obtained are valid only and exclusively if the tests are performed by authorized Independent Test laboratory.  

 

The following information gives an analysis and method of interpretation for the elements of the EN 13501 standard. 

 

reazione al_fuoco_sopraEN 13501-1.2007 fire reaction, article 12 and chart 2: Classification for Floors 

 

Generally the class of fire reaction are expressed in letters. A will be the best performance 

(Non-combustible), and F the lowest ( impossible to be determined ). 

 

To make a definition for a comparison the monogram fl (floor ) is used. 

 

So a further element to identify class A is a number 1 totally incombustible with no smoke production, number 2 is resistant to combustibility with some production of smoke. No other classes are permitted to have the same sub-classification. 

 

The last element that identifies the material; is smoke emission resulting from combustion. Classification s1 is compliance with a specific strict test criteria and classification s2 is for all other results that cannot be classified on s1. 

 

So according to this, the best performance for a floor will be the class A1fl, the second best will be A2fl-s1, the third best will be Bfl-s1 and so on to the worst classification being Ffl-s2. 

 

Clearly mentioned in the chapter 12 of the standard and on the chart n. 2, is the allocation of each class derived from the results of each total test. 

 

Single elements that can be classified within a specific class does not allow the entire product to be classified on the same class i.e. the use of a core material in class A1 do not means that the panels could be classified A1. 

 

A simple example: the presence of a minimum quantity of organic glue oil derivative will prevent an A1 classification due to the calorific power of the substance and the consequent smoke production. Similarly, the smallest presence of plastic edge trim will forbid the product to be classified in A1 class. 

 

All the calcium sulphate core products of JVP 4x4 panels are certified in class A1fl and A2fl-s1, while all the chipboard core products are certified in class Bfl-s1. 

 

The technical test to determine the fire reaction is undertaken according to EN ISO 1716, EN ISO 1182a, EN 13823 and EN ISO 11925-2 only full compliant test results will be considered before issuing a fire reaction classification. 

 

reazione al_fuoco_sottoEN 13501-2.2008 fire resistance, article 7.3.4: raised access floor classification 

 

Generally the raised access floor performance when under test is expressed by two or three alphabetical letters; R, E and I; 

 

R means the mechanical resistance of the tested elements that are subject to a specific load once on fire. The raised access floor is normally loaded with a 50 kg load placed at the top centre point of each panel under test and during the test the panel has to carry consistently this load consistently and not fail under it. 

 

E means the flame emission through the connection within the single elements. In the case of a raised access floor the flames are not supposed to pass through the joints within the panels during the whole period of the tests. 

 

I means the thermal insulation of the tested elements. With a raised access floor, the quantity of heat created underneath it has to be limited in transmission to the top surface. During the whole test the temperature at the top must not pass the stated limits. 

 

The second element of the classification is a number that quantifies the time of the test in minutes taken to satisfy the criteria of each of the letters and in the case of a raised access floor only two classes are considered i.e. 15 and 30 minutes. 

 

The third element required (not always mentioned) is the limit of the temperature of the test furnace, which in the case of a raised access floor could be at a reduced temperature curve identified with the letter R and the maximum temperature reached on the furnace will be 500°C. According to this, the best performance for a raised access floor will be class REI30, the second will be RE30, the third I30 while the lowest will be I15. 

 

In summary; to achieve the class REI30, which is the highest required class for a raised access floor, means that after 30 minutes of constant flame which burns underneath the raised access floor none of the following must occur: 

 

Failure of the panels loaded with 50 kg.

Passage of flame or smoke from within the edge of the panels.

The temperature at the top of the floor is above the required limits.

 

The fire reaction classification does not mean that the product has a good fire resistance or vice versa, the results of the two parts are the consequence of complex factors, only the total sum of the results can qualify the full system for classification on reaction in case of fire. 

 

All JVP 4x4 panels with calcium sulphate core and or with chipboard core are certified in class REI30r by a recognised and authorised independent test laboratory. The technical test to determine the fire reaction is done following the UNI EN 1366-6 guidelines and the fully compliant test results have to be considered before issuing any fire resistance classification.    

 

 

the conductivity & earthing, evaluating the facts

 

Raised Access Floor JVP 4x4, electrical conductivity.

 

The design of our Raised Access Floor has received considerable attention dedicated to the electrical earthing characteristics, as a result we are able to give total security regarding electrical earthing of the system for equi-potential bonding of buildings as required by the European Directive 106 within its 5th character “safety on use“and the EEC 17th edition for the security on electrical leakage and connection to the building general earth.

 

Our panels, fully encased in hot dipped galvanized steel are conductive by concept, irrespective of the type or quality of the core component. The electrical contact within the top and bottom surface, as well to the edge is secured by contact between the two steel sheets press formed by “welted pressing design” into a continuous steel envelope.

 

The pedestals, produced entirely in steel with corrosion protection by zinc passivation have full mechanical adjustment together with a substantial locking nut. Electrical continuity for the system is achieved through the pedestal head gasket which has four brass connectors which create an electrical bridge between each panel and the pedestal system.

 

This fully secures the electrical conductivity of our Raised Access Floor and will allow the simplest connection to the earthing system of the building to grant the equipotential bonding required by European rules.

 

With regard to EEC 17th edition the JVP 4x4 raised access floor system enables a simple and easy connection to the earth complying with the requirement to earth all the metallic components on a building that are at risk of being in contact with leakage of electricity.

 

A straight forward earth connection of one pedestal every 30m2 of floor area facilitates electrical resistance below 0, 5 ohm.

 

The advantage with the JVP design is that we can guarantee earthing for every single vertical pedestal.

 

 

the zincwhiskers phenomena, analysing the facts

 

Raised Access Floor JVP 4x4, electroplating and hot dipped galvanization.

  

Access floor systems designed with fully steel encapsulated panels, a fabrication type used in the majority of the worldwide markets to the extent of many millions of square metres each year, are finished with different types of top surface protection treatment such as: varnishing, electroplating and in our case; the hot dipped pre galvanization method, Sendzimir.

 

Protection by varnishing could potentially cause risks of dangerous toxic vapour and the generation of flames in the case of fire, whilst the other two treatments are totally incombustible.

 

However, in many cases particular study about zinc electroplating has been undertaken concerning the phenomena of “zincwhiskers” a reaction to stresses, which although this has never been irrefutably confirmed by scientific documentation or actively supported by any official international harmonisation of European Technical Standards, point out potential risks which might result from electroplated zinc particles which might over time break free from steel surfaces treated in this way and cause severe problems within the operation of highly sensitive electronic equipment.

 

The hot dipped galvanization treatment Sendzimir completely eradicates any kind of problems whatsoever, because the surface treated in this way is unable to suffer any adverse reaction by way of stresses and particles do not break free from this finish.

 

We only use galvanised steel in the production of panels for the JVP 4X4 access floor system and this is type: DX51Z100 steel protection with Sendzimir hot dipped pre galvanization a steel passivation made during steel manufacturing; is completely free from any risk of the generation of “zinc whiskers”. 

 

 

 
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