Pulsating pressures (think: engine combustion cycles, reciprocating pumps) don’t just rise and fall—they spike, dip, and oscillate in patterns that hold critical data. To capture them, your pressure scan valve’s sampling frequency needs to be fast enough, but not wastefully so. Here’s the formula.

The golden rule: Nyquist Theorem
You need to sample at least twice as fast as the highest frequency in the pulsation. For example:

· A pump pulsing at 100 Hz (100 cycles/second) needs a sampling frequency of ≥200 Hz.

But for safety, multiply by 5–10x. Why? Pulsations often have harmonics (higher-frequency “echoes”). A 100 Hz pump might have 500 Hz harmonics—so 1,000 Hz sampling ensures you capture them.

Step-by-step calculation:

1. Measure the pulsation’s fundamental frequency (f) using a temporary high-speed sensor (e.g., a 10 kHz accelerometer).

2. Estimate the highest harmonic (typically 5x f for most industrial systems).

3. Set sampling frequency to 10x that harmonic.

Example: For a diesel engine with f = 200 Hz (idle), harmonics reach 1,000 Hz. Sampling at 10,000 Hz (10x 1,000) guarantees you won’t miss spikes.

Avoid over-sampling:
A 100,000 Hz frequency sounds better, but it generates 10x more data—slowing down analysis and filling storage. For most tests, 10x the highest harmonic is enough.

Pro tip: Use a “burst mode” if your valve has it. It samples at high frequency only when a pulsation starts (triggered by a threshold pressure), saving data storage.

Stuck calculating? Share your system’s typical pulsation rate, and we’ll compute the needed frequency.