Testo 312-4 - Differential Pressure Measuring Instrument [SKU 0632 0327]
testo 312-4 - Differential Pressure Measuring Instrument
- Tightness testing and load testing on gas pipes
- Serviceability testing with air by pressure drop on gas pipes
- Pressure testing on drinking water and waste water pipes using air
- Automatic recording of measuring values over several hours
A variety of directives describe the tests which have to be carried out before commissioning water and gas pipes. The testo 312-4 differential pressure measuring instrument offers measuring processes for load and tightness tests as well as serviceability tests on gas pipes using air. It also enables the checking of static gas and gas flow pressures, as well as the nozzle pressure setting on gas burners or boilers.
These measurements are possible with the testo 312-4 differential pressure measuring instrument
- Tightness and serviceability testing by pressure drop on gas pipes in accordance with DVGW TRGI 2008
- Load testing on gas pipes in accordance with DVGW-TRGI 2008 using our high-pressure probe (can be ordered as an option)
- Pressure testing on drinking water pipes using water and with the support of the optional high-pressure probe in accordance with DIN 1988 (TRWI) and using air in accordance with the ZVSHK information sheet
- Pressure testing on waste water pipes using our high-pressure probe (can be ordered as an option)
- Checking the gas pressure regulator by recording the readings over a defined period (max. 25,000 readings)
- Checking the gas connection and gas flow pressure, as well as setting the nozzle pressure on gas burners and boilers
Practical features of the differential pressure measuring instrument
The testo 312-4 pressure measuring instrument offers a high level of operating convenience in order for you to carry out pressure measurement efficiently – for instance through preset measuring processes or the clear presentation of readings on the large display. The testo fast printer, which can be ordered as an extra, means you can produce measurement data printouts directly on site. The easyheat PC software is available to you as an option for data transfer and evaluation. Furthermore, probes which are also available for various measuring tasks can be attached to the differential pressure measuring instrument (e.g. high-pressure probe or thermocouple probe for temperature measurement).
testo 312-4 differential pressure measuring instrument, including battery and calibration protocol.
|Temperature - TC Type K (NiCr-Ni)|
|Measuring range||dependent on probe type used|
±0.4 °C (-100 to +200 °C)*
±1 °C (Remaining Range)*
|Differential pressure (internal sensor)|
|Measuring range||0 to 200 hPa|
±0.03 hPa (0 to +3 hPa)
±1.5 % of mv (+3.1 to +40 hPa)
±2 hPa or ±1 % of fsv (41 to +200 hPa)
|Pressure measurement (external probe)|
|Measuring range||0 to 25 bar|
±0.6 % of fsv (0 to 10 bar)
±0.6 % of fsv (>10 to 25 bar)
|General technical data|
|Dimensions||219 x 68 x 50 mm|
|Interface printer||Infrared interface|
|Measuring rate||auto 1 s to 24 h; fast 0,04 s|
|Memory||25,000 measuring values|
Pressure measurements on burners
Checking the gas pressure on burners is one of the standard measurements during services of domestic heating systems. This involves measuring the gas flow pressure and gas resting pressure of the system. The flow pressure, also called supplied pressure, refers to the gas pressure of the flowing gas and resting pressure of the static gas. If the flow pressure for gas boilers is slightly outside the 18 to 25 mbar range, adjustments must not be made and the appliance must not be put into operation. If the burner is nevertheless put into operation, it will not be able to function properly and, when the flame is generated, small explosions will occur and ultimately malfunctions; the burner will therefore shut down and the heating system will fail.
Pressure tests on gas pipes (load test)
The technical regulation for gas installations (in short: TRGI) is a binding and at the same time important regulation for skilled tradespeople. The TRGI governs how gas installations are to be planned, designed, serviced and maintained. This applies to all gas installations. This regulation is taken care of by the German Association for Gas and Water (DVGW). The TRGI 2008 is the current version. Amongst other things, this states that gas pipes are to be tested according to the construction phase (basic shell, completion and repairs). Load testing is one of the checks that plays a role in the application stated here: in this process, the material of a gas pipe is tested for stability and the connections for service life; this takes place prior to plastering over or concealment of the gas pipes. During load testing, the newly installed pipe, without fittings or gas appliances, is put under 1 bar pressure. The testing medium is air or inert gas. There must be no pressure drop detected during the test, which lasts at least 10 minutes.
Pressure tests on water pipes
According to the legal regulations of DIN EN 806-4, DIN 1988-7 and DIN 1610, drinking and waste water pipes are to be tested for leaks before being put into service by means of a pressure test with air, inert gas or water; they are also to undergo load testing with air or inert gas. However, for reasons of hygiene, it is best if the pipes remain dry until shortly before commissioning and do not undergo a leak test using water. A pressure test with air is also recommended to prevent metallic materials from corroding. The pressure test is split into two pressure-related parts where test pressure and time depend on the objective (load or leak). Leaks can usually be heard very quickly. If it is difficult to locate the leaks, the usual auxiliary tools and materials for gas pipes are used (spraying or brushing on foaming solutions).
Pressure tests on gas pipes (leak, load test)
The technical regulation for gas installations (in short: TRGI) is a binding and at the same time important regulation for skilled tradespeople. The TRGI governs how gas installations are to be planned, designed, serviced and maintained. This applies to all gas installations. This regulation is taken care of by the German Association for Gas and Water (DVGW). The TRGI 2008 is the current version. Amongst other things, this states that gas pipes are to be tested according to the construction phase (basic shell, completion and repairs). The following checks in particular play a role in the application stated here:
In this process, the material is tested for stability and the connections for service life; this takes place prior to plastering over or concealment of the gas pipes. During load testing, the newly installed pipe, without fittings or gas appliances, is subjected to 1 bar pressure. The testing medium is air or inert gas. There must be no pressure drop detected during the test, which lasts at least 10 minutes.
This test is for checking the pipe for leaks, with fittings and without gas appliances. The measuring instrument must not register any drop in pressure during the minimum 10-minute testing period (depending on the system volume); the test pressure is 150 mbar (previously 110 mbar).
Temperature measurements on radiators
When measuring temperatures on radiators, the flow and return temperature are recorded in particular and assessed by the tradespeople. The flow temperature is defined as the temperature of the thermal transfer medium (e.g. water) that the system is supplied with. The temperature of the medium flowing out of the system is correspondingly called the return temperature. To prevent losses within the heat distribution system and achieve a better level of efficiency, spot recording of flow and return temperatures is necessary. Implementation of relevant measures ultimately leads to hydraulic adjustment on the basis of knowledge about the flow and return temperatures. This defines a procedure with which every radiator or heating circuit of a flat radiator within a heating system is supplied at a set flow temperature with the precise amount of heat needed to achieve the ambient temperature required for the individual rooms. Flawed operating conditions will result in considerable excess consumption of electricity and heating energy. The German Energy Saving Regulation (EnEV) requires hydraulic adjustment for systems being set up or overhauled for this very reason.
Product brochure testo 312-2/-3/-4 (PDF, 690.7 kB)
Instruction manual testo 312-4 (PDF, 1.4 MB)