**Name of the standard**: National ESZ force standard 10 N

**Code designatio**n: ECM 150-10/21-065

**Year of publication**: 2021

**Department**: section 8011 CMI LPM Prague

**Guarantor**: Ing. Lukáš Vavrečka, Ph.D.

**Number of CMC lines provided**: 1

Mode | Scope | Uncertainty (k = 2) |

Tensile loading | 1 N – 10 N | 4·10^{-5} |

Compressive loading | 1 N – 10 N | 4·10^{-5} |

The National Standard of Force ESZ 10 N is a compact device with direct loading, which consists of one system of load bodies and a hanger that transmits the force to the force gauge to be measured. The load cells implement a unit of force in the range from 1 N to 10 N. The ESZ 10 N includes electrical power and control circuits for controlling the electric motors of the load cell systems and for balancing the load cell linkage.

The critical parts of the standard that define the unit of force are the load cells and the load cell linkage. The unit of force is defined as the force effect of the earth's gravitational field on the load cells of a given mass. When the load bodies are just weighted, a correction is made for the buoyancy of the surrounding air. The force exerted by the earth's gravitational field on the load bodies is transmitted to the force gauge to be measured via the suspension.

**Basic metrological characteristics:**

The force standard is intended for calibration of force standards in the force range from 1 N to 10 N under tensile or compressive loading. The best measurement capability of the standard is Wfsm=0,004 % of the measured force value. The best measurement capability of the standard is determined according to document EA-10/04 as the expanded uncertainty of the calibration of the standard with an expansion factor of k=2, corresponding to a probability of coverage for a normal distribution of P=95 %.

The force generated by the standard is given by the equation:

Where stands for:

F | ...........…. | the power generated by the standard, |

m | ...........…. | the weight of the load bodies, |

g | ...........…. | the gravitational acceleration at the location of the load bodies, |

ρ | ...........…. | air density at the location of the load bodies, |

ρ | ...........…. | density of load bodies. |