404a Operating Pressures (404a pt chart)

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What are the 404a operating pressures? Well, in this guide I provide you with a 404 pt chart which shows the common operating pressures for 404a at different temperatures.

404a Operating Pressure Chart  (404a pt chart) 

Temp(°F)Liquid Pressure (psi)Vapor Pressure (psi)Temp  (°C)
-490.90.3-45
-481.30.7-44.4
-471.71.2-43.9
-462.11.6-43.3
-452.62-42.8
-4432.4-42.2
-433.52.9-41.7
-4243.4-41.1
-414.43.8-40.6
-404.94.3-40
-395.44.8-39.4 
-385.95.3-38.9
-376.45.8-38.3
-3676.3-37.8
-357.56.8-37.2
-3487.4-36.7
-338.67.9-36.1
-329.28.5-35.6
-319.79-35
-3010.39.6-34.4
-2910.910.2-33.9
-2811.510.8-33.3
-2712.211.4-32.8
-2612.812-32.2
-2513.412.7-31.7
-2414.113.3-31.1
-2314.814-30.6
-22  15.414.6-30
-2116.115.3-29.4
-2016.816-28.9
-1917.516.7-28.3
-1818.317.4-27.8
-171918.2-27.2
-1619.818.9-26.7
-1520.519.7-26.1
-1421.320.4-25.6
-1322.121.2-25
-1222.922-24.4
-1123.722.8-23.9
1024.624.6-23.3
-925.424.5-22.8
-826.325.3-22.2
-727.126.2-21.7
-62827-21.1
-528.927.9  -20.6  
-429.828.8-20
-330.829.8– 19.4
-231.730.7– 18.9
-132.731.6-18.3
033.732.6-17.8
134.733.6-17.2
235.734.6– 16.7
336.7  35.6– 25.6
437.736.6-15.6
538.837.7-15
639.838.7-14.4
740.939.8-13.9
84240.9-13.3
943.142-12.8
1044.343.1-12.2
1145.444.3-11.7
1246.645.4-11.1
1347.846.6-10.6
144947.8-10
1550.249-9.4
1651.550.2-8.9
1752.751.5-8.3
185452.7-7.8
1955.354-7.2
2056.655.3-6.7
2157.956.6-6.1
2259.358-5.6
2360.659.3-5
246260.7-4.4
2563.462.1-3.9
2664.863.5-3.3
2766.364.9-2.8
2867.866.4-2.2
2969.267.8-1.7
3070.769.3-1,1
3172.370.8-0.6
3273.872.40
3375.473.90.6
347775.51.1
3578.677.11.7
3680.2 78.72.2
3781,880.32.8
3883.5823.3
3985.283.73.9
4086.985.44.4
4188.687.15
4290.488.85.6
4392.290.66.1
449492.46.7
4595.894.27.2
4697.6967.8
4799.597.98,3
48101.499.88.9
49103.3101.79.4
50105.3103.610
51107.2105.610.6
52109.2107.611.1
5311.2109.611.7
54113.3111.612.2
55115.3113.612.8
56117.4115.713.3
57119.5117.813.9
58121.7119.914.4
59123.8122.115
60126124.215.6
61128.2126.416.1
62130.5128.716.7
63132.7130.917.2
64135133.217.8
65137.3135.518.3
66139.7137.818,9
67142140.219.4
68144.4142.620
69146.914520.6
70149.3147.421.1
71151.8149.921.7
72154.3152.422.2
73156.8154.922.8
74159.4157.523.3
75162160.123.9
76164.6162.724.4
77167.3165.325
7817016825.6
79172.7170.726.1
80175.4173.426.7
81178.2176.227.2
8218117927.8
83183.8181.828.3
84186.7184.728.9
85189.5187.529.4
86192.5190.430
87195.4193.430.6
88198.4196.431.1
89201.4199.431.7
90204.5202.432.2
91207.6205.532.8
92210.7208.633.3
93213.8211.733.9
94217214.934.4
95  220.2218.135
96  223.4221.435.6
97226.7224.636.1
98230227.936.7
99233.423137.2
100236.8234.637.8
101240.2238.138.3
102243.6241.538.9
103247.124539.4
104250.6248.540
105254.2252.140.5
106257.8255.641.1
107261.4259 .341.7
108265.1262.942.2
109268.8266.642.8
110  272.5270.443.3
111276.3274.143.9
112280.127844.4
113284281.845
114287.9285.745.6
115291.8289.646.1
116295.8293.646.7
117299.8297.647.2
118303.8301.747.8
119307.9305.848.3
120312.1309.948.9
121119.13141494
122320.4318.350
123324.7322.550.6
124329326.851.1
125333.3331.251.7
126337.7335.652.2
127342.134052.8
128346.6344.453.3
129351.134953.9
130355.7353.554.4
131360.235.155
132364.9362.855.6
133369.6367.556.1
134374.3372.256.7
135379.137757.2
136383.9381.957.8
137388.8386.858.3
138393.7391.758.9
139398.7396.759.4
140403.7401.760
141408.8406.860.6
142413.941261.1
143419.1417.161.7
144424.3422.462.2
145429.6427.762.8
146434.9433.163.3
147440.3438.563.9
148445.8443.964.4
149451.3449.565
150456.8455.165.6

Read also: R410a Pressure Chart High and Low Side

psi: Pound per square inch, unit of pressure

FAQ

What is the normal suction pressure on a 404a walk in the freezer?

For R404A, the typical low-side pressure ranges from 55-70 psi, while the high-side pressure is around 210-250 psi. Variations can occur due to factors like ambient temperature and system load. If your cooler is located in a hotter environment, you might notice pressures trending toward the upper limits.

What are normal operating pressures for R404A?

The normal operating pressures for R404A in a walk-in cooler typically range between 55-70 psi on the low side and 210-250 psi on the high side. For example, during the summer months when ambient temperatures are higher, you might observe pressures on the higher end of these ranges due to increased thermal load.

How do you adjust the suction pressure in a 404A walk-in cooler?

To adjust the suction pressure, you can modify the refrigerant charge, clean the condenser coils, or adjust the expansion valve. For example, if the suction pressure is too high, you might need to reduce the refrigerant charge or clean the condenser coils to improve airflow.

What maintenance steps can prevent high suction pressure in 404A systems?

Regular maintenance such as cleaning condenser and evaporator coils, checking for refrigerant leaks, and ensuring proper airflow can prevent high suction pressure. Scheduling routine inspections can help identify and address issues before they lead to significant pressure increases.

What are the pressure control settings for 404A?

Typically, the cut-in pressure for the low-pressure control is set around 20-30 psi below the desired evaporator pressure, while the cut-out pressure is set approximately 10 psi below the desired evaporator pressure. The high-pressure control cut-out is generally set at 270-290 psi. For example, a bakery using a 404A system might set the cut-in pressure at 30 psi and the cut-out at 20 psi to ensure efficient operation.

What is the suction pressure on a 404A cooler?

The suction pressure for a 404A cooler typically falls between 55-70 psi. This range ensures that the refrigerant evaporates at the desired temperature in the evaporator. If the suction pressure falls outside this range, it might indicate an issue such as an overcharged or undercharged system.

What causes high suction pressure in a 404A system?

High suction pressure can be caused by overfeeding the evaporator, a dirty or blocked condenser, or an overcharged system. For instance, if a walk-in cooler’s condenser coils are dirty, it can restrict airflow and cause pressure to build up, leading to higher suction pressures.

How does ambient temperature affect the efficiency of a 404A walk-in cooler?

Ambient temperature affects the cooling load and the pressure within the system. Higher ambient temperatures can increase the thermal load, leading to higher operating pressures and reduced efficiency. Conversely, cooler ambient temperatures can reduce the load and improve efficiency.

What are the signs of an overcharged 404A refrigeration system?

Signs of an overcharged system include high head pressure, reduced cooling efficiency, and potential compressor overload. If the system is overcharged, it might also exhibit higher than normal suction pressures and an increase in energy consumption.

What is a good superheat for a 404A cooler?

A good superheat value for a 404A cooler is typically between 8-12 degrees Fahrenheit. This ensures that the refrigerant has absorbed enough heat without any liquid refrigerant returning to the compressor. For example, a walk-in cooler set to maintain a superheat of 10 degrees Fahrenheit will ensure efficient operation without risking compressor damage.

What is the subcooling temperature for 404A?

A typical subcooling value for 404A is around 10-15 degrees Fahrenheit. Proper subcooling ensures that the refrigerant is in its liquid form before entering the expansion valve, optimizing the cooling process. For example, achieving a subcooling temperature of 12 degrees Fahrenheit in a walk-in cooler can improve system efficiency and prevent operational issues.

How can insulation impact the performance of a 404A walk-in cooler?

Good insulation helps maintain the desired internal temperature by reducing thermal losses. This leads to lower energy consumption and more stable operating pressures. For instance, a well-insulated walk-in cooler will require less frequent cycling of the refrigeration system, enhancing efficiency.

What tools are necessary for regularly checking the pressure in a 404A system?

Essential tools include pressure gauges, a digital thermometer, and a multimeter. These tools help monitor system pressures, temperatures, and electrical parameters, ensuring the system operates within the specified ranges.

How often should pressure gauges be checked in a 404A walk-in cooler?

Pressure gauges should be checked at least monthly as part of routine maintenance. Regular checks help identify deviations from normal operating pressures, allowing for timely corrective actions to prevent major issues.

What causes high superheat in a walk-in cooler?

High superheat can be caused by a refrigerant undercharge, a restricted expansion valve, or a dirty evaporator coil. It indicates that the refrigerant has absorbed more heat than it should, reducing system efficiency. If a cooler’s evaporator coil is dirty, it can restrict airflow and lead to higher superheat values.

What should the superheat be for a walk-in cooler with a TXV?

For a walk-in cooler equipped with a Thermostatic Expansion Valve (TXV), the superheat should typically be set between 8-12 degrees Fahrenheit. The TXV helps maintain this superheat by adjusting refrigerant flow, ensuring optimal performance.

What are the risks of operating a walk-in cooler with incorrect pressure settings?

Operating with incorrect pressure settings can lead to reduced efficiency, higher energy consumption, and potential system damage. For example, if the suction pressure is too low, it can cause the evaporator coil to freeze, leading to inefficient cooling and possible compressor damage.

How does the frequency of door openings affect the pressure and temperature balance in a walk-in cooler?

Frequent door openings introduce warm air, increasing the cooling load and causing pressure fluctuations. This can lead to higher operating pressures and increased energy consumption. To minimize this effect, limit the frequency and duration of door openings.

What steps should be taken if a 404A cooler experiences frequent pressure fluctuations?

If frequent pressure fluctuations occur, check for issues such as refrigerant leaks, dirty coils, or faulty components. Regular maintenance and timely repairs can help stabilize the pressures. For instance, cleaning the condenser coils and ensuring adequate airflow can significantly reduce pressure fluctuations.

What is the low-pressure switch setting for a walk-in cooler?

The low-pressure switch is usually set to cut off the compressor if the pressure drops below 20-25 psi. This setting protects the compressor from running under low-pressure conditions, which can cause damage. For instance, a bakery using a 404A system might set the low-pressure switch to cut off at 22 psi to prevent compressor damage.

What causes high head pressure on a walk-in cooler?

A dirty or blocked condenser, an overcharged system, or inadequate airflow around the condenser can cause high head pressure. For example, if the area around the condenser is cluttered, restricting airflow, it can cause the head pressure to rise.

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