Kohtvibratsioon

Taustateave

The EC – Directive 2002/44/EC lays down minimum requirements for the protection of workers from risk to their health and safety arising or likely to arise from exposure to mechanical vibration.

The assessment of the vibration exposure is calculated in relation to a standardised 8h daily exposure value A(8). After establishing the A(8) value, this should be compared with the exposure action- and limit-values. As the Directive lays down minimum requirements, it is also vital to check legislation in each individual Member State of interest to find out if this legislation has stricter exposure values.

Depending on the daily Exposure Action Value (EAV) and the daily Exposure Limit Value (ELV), the employer has an obligation to take appropriate action in order to control the vibration exposure.

Kokkupuute rakendusväärtus (EAV)

Iga kord, kui töötaja puutub kokku kohtvibratsiooniga A(8), mis ületab kokkupuute rakendusväärtust 2,5 m/s², peab tööandja teostama töö riskianalüüsi ja tutvustama töötajale ettevaatusabinõusid. Lisateavet vaadake EÜ direktiivist 2002/44/EC ja liikmesriigi seadustest.

Kokkupuute piirväärtus (ELV)

Igal juhul ei tohi töötajad vibratsiooniga kokku puutuda rohkem kui on kohtvibratsiooni piirväärtus ELV (5.0 m/s²).

Soovitatav tegevus vähendamaks vibratsiooni mõju

Use only low vibrating power tools. This recommendation could be regarded as the most important one. Vibration data can often be found in the manufacturer's technical information.

Shorten the usage time of the tool. As the A(8) value is a function of both vibration value and exposure time, one alternative is always to cut down on the working time.

Service and maintenance of the machine. Follow the manufacturer's recommendations. It is especially important to maintain the cutting equipment and the rotating elements that can become unbalanced due to wear.

Kohtvibratsioonikalkulaator

This calculator was developed as an aid to perform calculation of vibration exposure and was carried out under the following conditions:

Equivalent vibration value, ahv,eq. Measured according to ISO 5349-1 or according to relevant measuring standard based on ISO 5349-1 for the specific power tool.

Typical daily exposure time, Texp. The exposure time is always less than the daily working time. For most power tools, the estimation of Texp comes from an international study (CEN Technical Report - “Guideline for the assessment of exposure to hand-transmitted vibration based on information provided by manufacturers of machinery”). For machine types not included in this report, the Texp has been estimated from time studies. See table 1.

The assessment of A(8) is thereby only valid for these conditions. If a machine is used in a non-standard working application or if the exposure time is not relevant, the assessment of A(8) should be made taking these factors into consideration.

Kasutusjuhend

The calculator is divided into two sections of which the left section immediately produces each power tool's individual A(8) exposure value, based on 8 hours usage time.

The right section is the actual calculator, which calculates each tool's partial exposure to any usage time if other than 8 hours. If the worker chooses to use multiple tools over the working day, the calculator produces their total A(8) exposure values as well.

Choose model of power tool. The chosen model's A(8) value and the model's equivalent vibration value ahv,eq will show next to the left section's model field. The model field adds one row for each model.

To calculate a new A(8) exposure value when using multiple power tools or for various user times, simply enter the specified tools' estimated daily working times into the white fields. Read the result for each tool from the column partial daily exposure. If you use multiple tools, the calculator will produce the tools' accumulated A(8) exposure value during the full working day in the cell below the partial daily exposure column.

The lights at the bottom will change with the A(8) value.
Green - The daily vibration exposure is below 2.5 m/s².
Yellow - The daily vibration exposure is above the exposure action value at 2.5 m/s².
Red - The daily vibration exposure is above the exposure limit value at 5 m/s².

To clear all cells and start again, click the "Reset form" button.

Kalkulatsioon registreerimata toodetele

A(8) rakendusväärtus on teada

The calculator has two options to include other hand-arm vibrating power tools as well. The simplest option is when the tools' rated A(8) exposure values are known.

Choose “other” from the model list. By selecting “other” the calculator automatically uses the typical vibration exposure time for that specified tool group. See table 1.

Edit the name in the model field (not necessary).

Enter the A(8) exposure value into the third column in the left section. Then use the calculator as described in section “Instructions for use”.

A(8) kokkupuuteväärtus pole teada

Kui A(8) kokkupuuteväärtus pole teada, määrake iga käepideme samaväärne vibratsiooniväärtus ahv,eq. Väärtuse ahv,eq määramiseks vajate iga käepideme ja töörežiimi kiirendusväärtust ahv. Kiirendusväärtus ahv on ruutjuur käepideme kolmel teljel mõõdetud vibratsiooniväärtuste ahw aritmeetilise summa ruutkeskmisest. Selle arvu saab seadme tootjalt.

Valem 1: ahw = ruutjuur summast a²hwx + a²hwy + a²hwz (1)

Samaväärne vibratsiooniväärtus ahv,eq on erinevate töörežiimide vibratsioonide summa. Kalkulaator kasutab siin väärtuse ahv,eq arvutamiseks väärtust ahv koos iga töörežiimi ajalise osaga ti. Väärtus ahv,eq arvutatakse igale käepidemele eraldi. Kuna kasutatakse ainult käepideme halvimat (suurimat) väärtust, tuleb kalkulaatorisse sisestada just see väärtus. Seejärel arvutab kalkulaator päevase kokkupuuteväärtuse A(8), mis kuvatakse kalkulaatori vasakpoolses osas. Kaheksatunnisele võrdlusperioodile standardiseeritud päevase kokkupuuteaja määramiseks kasutab kalkulaator kolmandat võrrandit, kus kasutab vastava seadme samaväärse vibratsiooni väärtust ahv,eq ja päevast kokkupuuteaega Texp. Vt tabelit 1.

Valem 2: ahveq = ruutjuur summast 1 jagatud T summa i=1 kuni n korda a²hvi korda ti (2)
Valem 3: A(8) = ahveq korrutatud ruutjuurega Texp jagatud 8 (3)

Choose “other” from the model list. By selecting other the calculator will automatically use the typical vibration exposure time for the specified tool group. See table 1.

Edit the name in the model field (not necessary).

Enter the worst (maximum) handle's ahv,eq value into the second column in the left section of the calculator. Now the calculator determines the daily exposure value A(8), which is shown in the third column in the left section of the calculator.

Tabel 1 - tüüpilised päevased kokkupuuteajad

Typical daily exposure times for the use of single power tools during an 8-h working day. From CEN-Technical report “Guideline for the assessment of exposure to hand-transmitted vibration based on information from manufacturers of machinery”.

Masina tüüp Kasutusala Tüüpiline kokkupuuteaeg
Ülakäepidemega mootorsaed Puuhooldus 2,4 tundi
Prof. mootorsaed <80 cm³ Logging farming, Landscaping 3,7 tundi
Prof. mootorsaed>80 cm³ Suured metsaraietööd 3,7 tundi
Trimmerid Haljastus 4,0 tundi
Võsalõikurid Teehooldus, haljastus 3,5 tundi
Hekilõikurid Haljastus 3,5 tundi
Lehepuhurid Omavalitsused 3,0 tundi
Servalõikurid Haljastus 3,0 tundi
Tükelduspingid (käeshoitav) Ehitus 1,0 tundi
Tükelduspingid (ratastel) Ehitus 2,5 tundi

Tähelepanu! Antud tüüpilised päevased kokkupuuteajad arvutati välitingimustes representatiivsel viisil. 90% juhtudel kõigist uuritud kasutusaladest oli päevane kokkupuuteaeg lühem kui tabelis olevad väärtused. Hinnanguliselt 10%-l uuritud kasutusaladest on kokkupuuteaeg pikem. Seega tuleb iga tööülesannet hoolikalt analüüsida ja kontrollida, kas selle vibratsiooniga kokkupuutumise aeg on pikem.

Tabel 2 - ajaline järjestus

Time sequences of the operating modes for chain saws and other power tools as described in CEN-Technical report “Guideline for the assessment of exposure to hand-transmitted vibration based on information from manufacturers of machinery”.

Masina tüüp Tühikäik Maksimaalvõimsuse pöörlemiskiirus Maksimaalkiirus
Ülakäepidemega mootorsaed 1/3 T 1/3 T 1/3 T
Prof. mootorsaed <80 cm³ 1/3 T 1/3 T 1/3 T
Prof. mootorsaed>80 cm³ 1/2 T 1/2 T
Trimmerid 1/2 T 1/2 T
Võsalõikurid 1/2 T 1/2 T
Hekilõikurid 1/5 T 4/5 T
Lehepuhurid 1/7 T 6/7 T
Servalõikurid 1/2 T 1/2 T
Tükelduspingid (käeshoitav) 1/7 T 6/7 T
Tükelduspingid (ratastel) 1/7 T 6/7 T