{"id":10503,"date":"2026-06-04T17:31:35","date_gmt":"2026-06-04T09:31:35","guid":{"rendered":"https:\/\/www.hginstrument.com\/?p=10503"},"modified":"2026-06-04T17:31:35","modified_gmt":"2026-06-04T09:31:35","slug":"installation-of-drainage-receiver-for-steam","status":"publish","type":"post","link":"https:\/\/www.hginstrument.com\/id\/installation-of-drainage-receiver-for-steam\/","title":{"rendered":"Installation of drainage receiver for steam measurement"},"content":{"rendered":"

Installation of drainage receiver for steam measurement<\/a><\/p>\n

In industrial steam flow measurement, orifice plate flowmeters have dominated due to their simple structure, high reliability, and wide applicability. The drainage receiver (condenser) as the core component of the pressure guiding pipe system, its proper installation directly determines the accuracy and long-term stability of the flow measurement.<\/p>\n

I.\tPrinciple of steam measurement by orifice flowmeter and the background of the emergence of the drainage receiver<\/p>\n

\"Installation
Installation of drainage receiver for steam measurement<\/figcaption><\/figure>\n

The orifice flowmeter is based on the throttling principle. When a fluid flows through the orifice plate, a differential pressure is generated, and the square root of this differential pressure is proportional to the flow rate. For steam, typically, ring chamber pressure tapping or flange pressure tapping is used. The high-pressure and low-pressure side pressure signals are transmitted to the differential pressure transmitter through the pressure guiding tube. However, steam has extremely high latent heat of vaporization and temperature (saturated steam at 100-250\u2103, and superheated steam up to over 400\u2103). If the high-temperature steam directly enters the pressure guiding tube and the transmitter, it will cause: \u2460 The sensitive element of the transmitter will be damaged due to overheating or zero drift; \u2461 Uneven condensation of steam in the pressure guiding tube leads to two-phase flow, resulting in severe fluctuations in the differential pressure signal; \u2462 Unequal condensate levels on the positive and negative pressure sides introduce static pressure errors. Therefore, it is commonly adopted to install a drainage receiver (also known as a condenser or steam drainage receiver) near the pressure tapping port to force the steam to condense into liquid water in the tank and maintain a constant and equal condensate level. This ensures a reliable isolation of the high-temperature steam from the transmitter and simultaneously transmits a stable static pressure.<\/p>\n

The drainage receiver is not merely a simple container; it is a sophisticated component that integrates functions of condensation, liquid storage, isolation, and pressure stabilization. Its typical structure consists of a carbon steel or stainless steel cylindrical body with a volume ranging from 0.5 to 5 liters. The design pressure is not less than the pipeline design pressure. There are exhaust\/flush water ports, pressure guiding pipe interfaces, and discharge ports at the top and bottom respectively. Under proper installation conditions, the area above the liquid level in the drainage receiver is the steam condensation zone, while the area below the liquid level is the full liquid zone. Through the pressure guiding pipe, the pressure of the pure liquid phase is transmitted to the transmitter, completely eliminating phase change interference.<\/p>\n

\"2\"
2<\/figcaption><\/figure>\n

II. General installation specifications for drainage receiver
\nWhether it is saturated steam or superheated steam, the following installation specifications for the drainage receiver are all baseline requirements that must be adhered to. Violating any of them will result in significant measurement errors or system failure.<\/p>\n

1.\tGeometric position and orientation
\n\u2022 Adjacent to the pressure tapping point: The drainage receiver should be installed directly above or below the pressure tapping valve (the root valve) of the process pipeline? Correct practice: For steam, vertical upward pressure tapping (extracting from the top of the pipeline) must be adopted. The installation position of the drainage receiver must be higher than the pressure tapping port, and it should be as close to the root valve as possible to minimize the pressure guiding pipe from the pressure tapping port to the drainage receiver (usually \u2264 500mm), avoiding excessive condensation of steam in this section which may cause unequal liquid columns.
\n\u2022\tAbsolutely uniform height: The centerlines of the two drainage receivers on the positive and negative pressure sides must be on the same horizontal plane, and the height difference should be controlled within \u00b12mm. This is a necessary condition to ensure that the transmitter output is correct at “zero differential pressure”. If the drainage receivers are not at the same level, even if the pressure before and after the orifice plate is equal, the transmitter will generate false differential pressure due to the static pressure difference of the liquid columns on both sides.
\n\u2022\tVertical installation: The main body of the drainage receiver should be strictly vertical to ensure that the liquid level inside the tank remains level. The pressure guiding pipe interface is usually located at the center of the tank bottom to ensure that the pressure guiding pipe is always filled with condensate water and there are no air bubbles accumulation.<\/p>\n

2.\tThe slope and direction of the pressure guiding pipe
\nThe pressure guiding pipe from the drainage receiver to the differential pressure transmitter must be inclined downward throughout its entire length (with a slope of \u2265 1:10), and there must be no “bag-shaped” bends. This is to ensure that the gas can naturally flow towards the exhaust valve at the transmitter location and that the liquid is continuous and stable. The transmitter should be installed at the lowest point of the entire pressure guiding system and be equipped with a 3-way manifold and a drain valve. Special emphasis: The position of the transmitter must be at least 300mm below the bottom of both drainage receivers to maintain the full liquid state of the drainage receiver by the force of the liquid column.<\/p>\n

3. Water filling and exhaust of the drainage receiver
\nDuring the initial operation or after maintenance, it is necessary to manually fill the drainage receiver through the top plug or water filling valve until it is completely filled, and to remove all air from the tank and the pressure guiding pipe. For the steam system, it is strictly prohibited to rely on the steam to condense by itself to establish the liquid level – during the initial stage, the steam cools the tank violently, and the cooling rates on both sides are inconsistent, resulting in severe fluctuations in pressure difference and even causing the transmitter to overload. The water filling should use clean and softened water to avoid the deposition of dissolved solids.<\/p>\n

\"3\"
3<\/figcaption><\/figure>\n

4. Root valve and discharge accessories
\nEach set of drainage receiver should be equipped with: root valve (gate valve or ball valve) at the pressure tapping port, drain valve for drainage receiver (located at the bottom of the tank), drain valve for the pressure guiding pipe (located at the lowest point in front of the transmitter), and 3-way manifold \/ 5-way manifold. The exhaust\/inlet port at the top of the drainage receiver must be tightened after it is filled with water to prevent steam leakage.
\n\u26a0\ufe0f Engineering Warning:
\nMeasurement of superheated steam at a chemical plant
\nThe drainage receivers were not set up at an equal height and the transmitter was located above the drainage receivers. After the equipment was put into operation, the differential pressure signal was reversed and fluctuated by more than 30%. Upon inspection, it was found that the water in the positive pressure side drainage receiver was blown dry by the steam, and the high-temperature steam directly hit the transmitter, causing the silicone oil to carbonize. Later, it was reinstalled in accordance with the specifications, and the fault was eliminated.<\/p>\n

III. Comparison table of core differences in the design of saturated steam and superheated steam drainage receivers<\/p>\n

\"04\"
04<\/figcaption><\/figure>\n

IV Step-by-step planning: Establish standardized operating procedures (SOP) for the drainage receivers<\/p>\n

Regardless of the type of steam, following the 12-step setup process below can minimize human errors to the greatest extent.
\n1. Drawings verification: Confirm the installation direction of the orifice plate and the orientation of the pressure tapping port (0\u00b0 or 45\u00b0 for horizontal pipelines? Top tapping 0\u00b0 for steam);
\n2. Prefabricated brackets: Weld two independent brackets directly above the pressure tapping port, ensuring that the brackets can bear the weight and have adjustable heights (adjust the level using U-shaped bolts and nuts);
\n3. Install the root valve and the drainage receiver: Connect the short pipe, place the drainage receiver in position, use a laser level to adjust the centers of the two tanks to be at the same level with an error of \u2264 1mm, then lock the bracket;
\n4. Connect the pressure guiding pipe: Lead out a \u03a614\u00d72 stainless steel pipe from the bottom of the drainage receiver, lay it along the preset slope (>1:10) to the transmitter cabinet, set pipe clamps every 1.5m;
\n5. Installation of the transmitter and the 3-way manifold: The transmitter should be at least 300mm below the lowest point of the drainage receiver (for superheated steam, 600 to 1000mm is recommended);
\n6. System pressure test: Seal the transmitter end, introduce nitrogen at 1.5 times the working pressure from the exhaust port of the drainage receiver, and check for leaks at the welds and joints;
\n7. Water filling and drainage: Open the top plug of the drainage receiver, use a dedicated injection pump to inject deionized water, and slightly open the drain valve of the 3-way manifold at the same time, until no bubbles are discharged, then tighten the plug.
\n8. Zero point calibration: Close the root valve, open the balance valve, and the transmitter output should be 0% (or corresponding 4mA). If there is any deviation, adjust the zero point.
\n9. Startup of warm-up pipe: For saturated steam, fully open the root valve by 1\/4 turn, preheat for 30 minutes, then fully open it again; for superheated steam, partially open the inlet valve of the condensation ring, monitor the tank wall temperature and fully open the valve when the temperature drops below the boiling point by 20\u2103.
\n10. Check the balance valve: When putting it into use, first open the valve on the high-pressure side, then close the balance valve, and finally open the valve on the low-pressure side. Reversing the sequence will result in unidirectional overpressure.
\n11. Record initial parameters: Record the ambient temperature, the tank wall temperature, and the output of the transmitter of the drainage receivers on both sides.
\n12. Regular inspection: Check the liquid level of the drainage receivers every shift (by measuring the temperature difference between the upper and lower parts of the tank body, or using an external magnetic level gauge), and discharge the wastewater once every quarter.<\/p>\n

The technical manuals of instrument manufacturers such as Rosemount from the United States and Yokogawa from Japan all strongly recommend: For superheated steam, a sufficiently long cooling pipe must be installed before the drainage receiver, and the heat dissipation must be calculated. The simplified formula is recommended to estimate the length of the cooling pipe: L = (Q\u00b7k) \/ (\u03b1\u00b7\u0394T\u00b7\u03c0d), where Q is the latent heat of steam condensation, \u03b1 is the natural convection coefficient of air, and it can be quickly evaluated based on the steam temperature, ambient temperature, and pipe diameter.<\/p>\n

The drainage receiver may seem like just a cast iron or stainless steel “cylinder” in the differential pressure guide line, but it undertakes multiple responsibilities in steam flow measurement, such as phase change isolation, static pressure transmission, and temperature barrier. For saturated steam, the key lies in “equal liquid level and anti-steam crossover”; for superheated steam, the core is “strong cooling and anti-steam vaporization”. With the industrial digital transformation, although some scenarios have switched to wireless pressure transmitters or direct mass flow meters, the combination of orifice plates and drainage receiver will remain the mainstream for high-temperature and high-pressure steam measurement in the next 20 years, thanks to its cost and high-temperature and high-pressure resistance characteristics. Installation of drainage receiver for steam measurement is very necessary. <\/p>","protected":false},"excerpt":{"rendered":"

Installation of drainage receiver for steam measurement In industrial steam flow measurement, orifice plate flowmeters have dominated due to their simple structure, high reliability, and wide applicability. The drainage receiver (condenser) as the core component of the pressure guiding pipe system, its proper installation directly determines the accuracy and long-term stability of the flow measurement. …<\/p>\n

Installation of drainage receiver for steam measurement<\/span> Read More »<\/a><\/p>","protected":false},"author":4,"featured_media":10505,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[2352],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/posts\/10503"}],"collection":[{"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/comments?post=10503"}],"version-history":[{"count":0,"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/posts\/10503\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/media\/10505"}],"wp:attachment":[{"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/media?parent=10503"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/categories?post=10503"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hginstrument.com\/id\/wp-json\/wp\/v2\/tags?post=10503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}