Is the vacuum degree of Bernoulli equation negative?

The vacuum degree of Bernoulli equation will not be negative.

Bernoulli equation describes the relationship among velocity, pressure and height of fluid at different positions. In Bernoulli equation, vacuum degree is usually expressed as the difference between absolute pressure and atmospheric pressure. Because the vacuum degree is a relative value, it can only be non-negative. If the vacuum degree is negative, it means that the absolute pressure is less than atmospheric pressure, which is physically unreasonable. Therefore, according to the definition and physical principle of Bernoulli equation, the vacuum degree will not be negative.