humimeter RH5.1 - paper hygrometer with a sword probe

The humimeter RH5.1 is a paper moisture meter with a sword probe, made for measuring moisture in stacks of paper and board and for continuous climate control in printing houses and paper stores. It is the more affordable variant of the proven humimeter RH5 - the same housing, the same probe and the same functions, without the case and the rubber cover, and with a slightly wider calibration tolerance.

Art. no. 11994 - humimeter RH5.1, paper moisture meter with a sword probe.

Application

The meter measures the relative humidity of the air in the gap between the sheets. Once conditions inside the stack have equalised, that air humidity corresponds to the moisture of the paper, so the reading from the sword probe describes the state of the whole ream rather than its surface alone. The same instrument therefore checks both the paper and the climate of the hall.

Typical uses are checking paper at goods intake, before printing and before binding, documenting the conditions in a store, and settling complaints about cockling, wrinkling and colour registration problems - which almost always come from a difference in humidity between the paper and the hall.

How a measurement is taken

1. Equalise the temperature first. The instrument has to be at the same temperature as the paper being measured. The manufacturer states that a difference of just 1 °C causes an error of 0.6 to 6.3 % - the larger, the higher the humidity. A meter brought from a cold store into a warm hall has to be put down until its temperature reading matches the real one.
2. Push the probe about 10 cm into the stack, straight, so as not to bend the aluminium sword. In heavy stacks use the sword sleeve (art. no. 10451) and after the measurement pull it out of the stack with the sword sleeve extractor (art. no. 10523). The sleeve also has to equalise its temperature with the sword.
3. Every 10 seconds or so push it a few centimetres deeper, until the target depth is reached. Going in gradually protects the probe and speeds up the equalisation.
4. Wait for the reading to stabilise and freeze it with the hold function or store it in the logger.

Main features Relative air humidity 0 to 100 % with a resolution of 0.1 % RH Temperature -10 to +60 °C with a resolution of 0.1 °C, switchable °C / °F Dew point calculated over the range -55 to +60 °C Sword probe 295 mm long, pushed between the sheets without damaging the paper Hold function and an automatic and manual logger for 10 000 readings with measuring point reports Backlit matrix display 128 × 64 Multilingual menu Powered by commonly available AA batteries

Technical data

Scope of delivery

• humimeter RH5.1 moisture meter with a sword probe
• 4 alkaline AA batteries
• operating manual

There is no case and no rubber cover in the box - unlike the RH5, where both are part of the delivery. A case can be ordered separately.

Extended accessories

• Art. no. 15427 - EVA case for the humimeter RH6, RH5 and RH5.1
• Art. no. 10451 - sword sleeve made of stainless steel, for work in heavy paper stacks. It fits all RH5 versions (RH5, RH5.1 and RH5.2) and the RH6, since they all have the same sword. Before the reading the sleeve has to equalise its temperature with the sword.
• Art. no. 10523 - sword sleeve extractor for pulling the sleeve (art. no. 10451) out of a heavy stack, steel with a plastic handle. It is meant for the sleeve only, not for pulling out the meter.
• Art. no. 10072 - calibration device for the sword probe, 10 × 7 × 4 cm, 160 g
• Art. no. 10352 - certified calibration ampoules, set of 5 at 50 % RH
• Art. no. 10005 - certified calibration ampoules, set of 5: 2 × 35 % RH, 1 × 50 % RH, 2 × 80 % RH
• Art. no. 10403 - factory calibration certificate, adjustment protocol supplied with air humidity meters
• Calibration certificate with PCA accreditation - an alternative to the factory certificate (art. no. 10403). We calibrate the meter in an accredited Polish laboratory (PCA, the Polish Centre for Accreditation) and ship it to the customer together with the certificate; the certificate 10403 is then not needed.
• Art. no. 11131 - calibration and adjustment of the device at the manufacturer’s service

RH5 or RH5.1

Both meters share the same housing of 441 × 74 × 33 mm, the same 295 mm sword probe, the same weight of 310 g and an identical set of functions: relative humidity, temperature, dew point, hold and a logger for 10 000 readings. There are two differences.

• Calibration accuracy. The RH5.1 is ±2.0 % RH, the RH5 is ±1.5 % RH. When checking paper in the usual 40 to 60 % RH range, half a percentage point rarely changes a decision; when documenting conditions for a complaint it can matter.
• Scope of delivery. The RH5 comes with a rubber cover and a case, the RH5.1 with batteries only. If the meter is going to travel between stores and halls, it is worth adding the case (art. no. 15427) to the RH5.1 or choosing the RH5 from the start.