{"id":12965,"date":"2020-03-18T11:13:35","date_gmt":"2020-03-18T16:13:35","guid":{"rendered":"https:\/\/blog.wika.com\/us\/\/?p=12965&post_date=20200318102447"},"modified":"2025-12-10T13:44:01","modified_gmt":"2025-12-10T18:44:01","slug":"two-process-transmitters-for-differential-pressure-measurement","status":"publish","type":"post","link":"https:\/\/blog.wika.com\/us\/knowhow\/two-process-transmitters-for-differential-pressure-measurement\/","title":{"rendered":"Better Together: The Advantages of Using Two Interconnected Process Transmitters for Differential Pressure Measurement"},"content":{"rendered":"

Liquid level monitoring reaches a new height with WIKA\u2019s innovative solution: a system that uses two interconnected process transmitters for differential pressure measurement. This configuration is extremely precise, easy to install and use, and not susceptible to temperature variations.<\/span><\/b><\/span><\/p>\n

Originally designed to measure pressure before and after the fluid encounters an interruption, a\u00a0differential pressure transmitter can also determine liquid levels\u00a0by calculating the differential pressure between the liquid and gaseous phases of the fluid inside a closed tank. <\/span>The main problem, however, is that the small pipe (capillary) used to connect those two phases is subject to Gay-Lussac\u2019s Law: Within an enclosed system, the pressure of a gas is directly proportional to its temperature. In other\u00a0words, higher temperatures lead to higher-than-actual pressure readings\u00a0<\/span>(see Part 1 of this series<\/a>).<\/p>\n

Differential Pressure Measurement with Two Interconnected Process Transmitters<\/h2>\n

WIKA has developed a solution to the challenges of temperature fluctuations and inaccurate readings. Our innovative system takes two of the same process transmitter, such as the CPT-2X <\/a>or IPT-2X<\/a>, and connects them via a signal cable.<\/p>\n\n

\"Level

Figure 3: Level measurement using two interconnected process transmitters<\/p><\/div>\n \n

In this configuration, the subordinate process transmitter measures the gas pressure (P1<\/sub>) and communicates that reading to the principal over an internal bus (Figure 3). The principal transmitter measures the liquid pressure (P2<\/sub>) and then calculates the difference between P1\u00a0<\/sub>and P2<\/sub>. Using that difference, as well as pre-programmed parameters such as the tank\u2019s geometric variables and the liquid\u2019s specific density, the principal is able to determine the liquid\u2019s precise volume and level. It then sends that value to a control room and\/or displays it on the transmitter as a digital or analog signal. The principal also parameterizes and powers the subordinate.<\/p>\n

Without needing to use capillaries, this system handles even wide temperature fluctuations with ease. Its accuracy equivalent is up to 0.05 % of the set span. Furthermore, the signal cable is not susceptible to capillary-related failures.<\/p>\n

Pressure Transmitters vs. Process Transmitters
\nfor Differential Pressure Measurement<\/h2>\n

In theory, this system could work with pressure transmitters as well as process transmitters. However, using pressure transmitters would require several additional components:<\/p>\n