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Is a safety valve required if the pump cannot exceed its nominal pressure, and can the Hermetry alarm replace it?

Is a safety valve required if the pump cannot exceed its nominal pressure, and can the Hermetry alarm replace it?

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Translated from Türkçe by AI ·

Hi, I’m normally a software developer, but I set up the hot water line monitoring at my uncle’s dairy business, so the question is a bit from the outside.The line is: boiler, a circulation pump (maximum head in the catalogue around 4,8 bar), piping and heat exchanger. The line components were selected for 6 bar. The installer wants to fit a pressure relief valve (PRV), and my uncle says “the pump can’t reach 6 anyway, it’s wasted money”. I connected the pressure transmitter to Hermetry via ESP32, it comes in as p_bar, and I was thinking of setting an alarm at 5,5 bar.I have two questions: if the pump physically cannot exceed its nominal pressure, is a PRV really necessary? Second, I saw a section called Hermetry Safe on the forum, it looks like a safety monitoring product. Can we open it and use it instead of a valve? I couldn’t find it in the device menu.

Ağ geçidi yine bağlanıyor…
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Translated from Türkçe by AI ·

I was also wondering about Safe, I think it’s unlocked with a separate license. I guess we need to contact sales.

Sahadan selamlar.
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Translated from Türkçe by AI ·

Short answer to both: install a PRV, even if you have Safe, it does not replace the valve.On the valve: the pump’s discharge head is not the only pressure source. In a closed line, water expands when it heats up, and if a section on the heat exchanger side gets trapped while both valves are closed, pressure rises independently of the pump as the temperature goes up. The same happens if the boiler’s own control fails. The pump scenario protects you, but the thermal expansion and wrongly closed valve scenarios do not. Regulations already require mechanical safety for pressurised equipment, so your installer is right.On Hermetry: Safe has no page of its own in the documentation, so you need to ask sales how it works, as Ergun said. But whatever software product it is, I don’t think it will replace a mechanical valve; monitoring and protection are separate layers.What you can do today is set up monitoring well. In the profile, on the Alarm rules tab, a Threshold rule with two levels:

"severities": [
  { "severity": "CRITICAL", "condition": { "key": "p_bar", "op": ">", "value": 5.6 } },
  { "severity": "MAJOR",    "condition": { "key": "p_bar", "op": ">", "value": 5.0 } }
],
"debounce": { "mode": "count", "raise": 3, "clear": 3 },
"hysteresis": 0.2

Also add a Device offline rule. If the transmitter or ESP32 goes silent, you should be notified, so a silent sensor doesn’t look like everything is fine.

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Accepted solution♥ 5

Translated from Türkçe by AI ·

Honestly, I had never considered thermal expansion. I explained it to my uncle with this example and he was convinced, so a PRV set to 6 bar was installed. I set up the alarm rule as you wrote it, only on the first day it gave two MAJOR alerts at 5.0 bar in the morning when the boiler kicked in, so I raised the debounce to 5 readings, and now it’s calm. The offline rule has been added too. Thanks a lot, Esra.

Ağ geçidi yine bağlanıyor…
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Translated from Türkçe by AI ·

I also noted the thermal expansion example, and we had the same discussion in our boiler room. I’ll ask about Safe separately, but I think the valve question is closed.

Sahadan selamlar.
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